From fish kill to world-record pursuit — the story of rebuilding
a trophy coppernose bluegill fishery from the bottom up.
In the world of trophy bluegill fishing, they're called slabs — coppernose bluegills so big they barely look real. On a quiet five-acre pond in northern Alabama, not far from Huntsville, pond owner Sarah Parvin was on the verge of growing one for the record books. Decades of careful management had transformed her pond into something remarkable: a dedicated coppernose bluegill fishery producing fish that turned heads across the industry. They called it the Slab Lab, and it was living up to the name.
Then, on a hot July morning, it started.
First one fish belly-up near the bank. Then another. Within hours, thousands of trophy coppernose bluegill were bobbing lifeless at the surface — years of careful management deteriorating in the Alabama heat. What had gone wrong?
What could have been the end of the story became the beginning of a new one. Natural Waterscapes partnered with Sarah and rallied multiple industry leaders to do something rarely attempted at this scale: a complete reset of both the water column and the sediment. Not a band-aid. Not a "wait and see." A deliberate, science-driven intervention to rebuild the Slab Lab from the bottom up. Today, the results are speaking for themselves: phosphate locked in the sediment, a food web showing robust signs of recovery, and a pond that's not just bouncing back but being rebuilt better than before.
This is that story.
The Slab Lab started roughly thirty years ago as a pond built from scratch by Sarah's father, Dennis Olive. Like many private ponds in the Southeast, it was originally managed for bass and bluegill — but Sarah pivoted the entire fishery toward a single, ambitious goal: growing world-record coppernose bluegill.
It was working. Years of selective harvest, precision feeding, and relentless daily management had produced fish that turned heads across the industry. Features in Mossy Oak Gamekeeper, Outdoor Life, ESPN, Barstool Outdoors, and Major League Fishing brought national attention. By late 2024, shock surveys were producing coppernose registering at 250%+ on the relative weight chart — 8-inch fish weighing what most 10-inchers weigh. The world record was in sight.
Then 2025 hit hard. Back-to-back winter storms froze the pond solid for eleven straight days — a worst-case scenario for a subtropical species. Fish losses, a supercharged algae bloom, and an emergency aeration response followed. The team stabilized and recovered, but the system was stressed and loaded with nutrients heading into summer. As Sarah put it: they knew they were flying too close to the sun, taking big risks for big rewards. This was the price.
Sarah Parvin with a trophy coppernose bluegill at the Slab Lab.
In July 2025, a regional heat dome settled over the South, pushing surface water temperatures past 92°F. The Slab Lab had been managed for years under a traditional "Green is Good" philosophy: heavy nutrient loads driving dense phytoplankton blooms, keeping visibility between 12 and 18 inches to maximize biomass production. The water looked productive. Underneath, the pond was a system on the brink.
The Slab Lab is a relatively shallow pond, and temperature profiles showed little variation from top to bottom. But the sediment layer was a different story — completely anoxic and loaded with toxic gases from years of decomposing organic muck. Then the weather turned. A heavy rainfall event dropped roughly four inches of cool, 55°F rain onto 92°F surface water, accompanied by sustained winds of 12 to 15 miles per hour. In shallow water, that kind of wind energy can disturb several inches of sediment directly. The cold rain and wind combined to rapidly mix the pond, pulling ammonia, hydrogen sulfide, and oxygen-depleted water off the bottom and distributing it throughout the water column. In a pond this loaded, it was a death sentence.
As the team later described it: it was a perfect storm. Never just one thing, but several compounding factors all hitting at once.
When the anoxic bottom water mixed with the surface, the accumulated ammonia exerted a massive chemical oxygen demand. Converting just 1 mg/L of ammonia to nitrate requires approximately 4 mg/L of dissolved oxygen. The ammonia from the Slab Lab's bottom sucked the oxygen out of the entire water column. Fish that were already stressed from turbidity, pH swings, and the heat were pushed past the tipping point. As soon as that unionized ammonia spiked, they were done.
Dissolved oxygen at 0.07 mg/L. Effectively zero. The result was catastrophic. Trophy-class coppernose bluegill, years of genetics, selective harvest, and careful management, gone in a matter of hours. This wasn't a recreational pond that lost some bass. This was a nationally recognized fishery on the verge of producing a world-record fish.
When fish die and decompose in large numbers, they release enormous amounts of phosphorus and ammonia back into the water. Add that to the phosphorus already cycling out of the disturbed sediments, and the result is a nutrient bomb that can fuel toxic cyanobacteria blooms for years, even decades. The cyanobacteria was already there: Microcystis at the surface, Phormidium rising from the bottom in dark, leathery mats that people often mistake for string algae. Without intervention, the Slab Lab wasn't looking at a setback. It was looking at a cascading failure.
Sarah needed help. She made the call.
Thousands of coppernose bluegill lost in a single morning. July 2025.
The "Green is Good" approach to pond management is a traditional limnological axiom: high nutrient loads create dense phytoplankton blooms that shade out aquatic weeds and fuel the food chain from the bottom up. For decades, this was the standard for biomass production in aquaculture. And on the surface, it appeared to work. The problem was threefold. First, the dense blooms were dominated by cyanobacteria, which zooplankton can technically consume but derive almost no nutritional value from. Cyanobacteria lack the essential fatty acids, lipids, and sterols that zooplankton need to survive and reproduce, making them the nutritional equivalent of empty calories. Second, the heavy bloom was choking out sunlight to the bottom of the pond, smothering benthic habitat and preventing the growth of beneficial organisms in the sediment. Third, the excess nutrients that weren't being consumed were settling into the muck, building a massive phosphorus reserve that would continue to fuel blooms from below for years. All that apparent productivity was a biological dead end, and the system was building toward exactly the kind of catastrophic failure that hit in July.
When Natural Waterscapes got the call from Sarah, Heather didn't hesitate.
Before Heather even landed in Alabama, the team had already shipped RapidBac, a liquid nitrifying bacteria, because they knew ammonia levels would be dangerous after a fish kill of this magnitude. Sarah had already sent a water sample to the Natural Waterscapes lab in Pennsylvania. Regardless of what those numbers said, the team wanted product in the water as soon as possible.
The plan went far beyond cleanup. The goal was to take as much data as possible, as quickly as possible, so they could look at what went wrong and build a management plan to bring this fishery back. "We can just start reacting," Heather explained, "but let's learn from it. Because if we don't know all the factors that led this to where it's at today, then we know it's going to happen again."
Heather arrived with Hannah from Natural Waterscapes and went straight to the Slab Lab that evening. They grabbed dissolved oxygen readings at three different points around the pond, establishing multiple reference points rather than relying on a single measurement. They were back at dawn the next morning to collect the same readings again. The pond was running on fumes.
Then they did something most water testing misses entirely. Instead of just pulling surface samples, they lowered a deep water sampler to just above the sediment layer at the bottom of the pond. "Sometimes when you look at water quality from just surface samples, you can get a completely different picture of the health of a water body," Heather explained. "When we take samples from the deep, right at the interface with the organic muck, it can paint a completely different picture." In this case, the nutrient levels at the bottom were actually higher than at the surface.
Surface orthophosphate, the form of phosphorus that directly fuels algae growth, measured at 1.3 mg/L. For context, the target for a healthy fishery is below 0.05 mg/L. The Slab Lab was running at more than 26 times higher than optimal levels.
Cyanobacteria samples confirmed what they could already see and smell. The species identified were Microcystis, the colony-forming surface species that produces microcystin, Phormidium, a benthic species that grows on the bottom and rises to the surface in dark mats, and Planktothrix as well. Toxin samples were sent to GreenWater Laboratories in Florida and came back positive for all three categories: microcystin, anatoxin, and saxitoxin. Nobody was getting in that water without gloves.
Sarah was ready. "I have zero qualms about talking about how bad this water is," she said, "because we're going to fix it. And that's all that matters at the end of the day."
In the weeks following the July assessment, the data came back piece by piece, and each result confirmed that the Slab Lab's problems ran deeper than anyone could see from the surface.
The sediment phosphorus fractionation test revealed the full scope of the problem. This test quantifies how much reactive phosphorus is stored in the muck and how readily it can release back into the water. The results were staggering: approximately 20 pounds of reactive phosphorus per centimeter of depth in the top 10 centimeters of sediment. Total available phosphorus stored in the water column and benthic layer combined: over 1,000 pounds. Considering that just one pound of phosphorus can fuel 500 pounds of algae, this represented a massive and self-sustaining bloom engine that would keep firing indefinitely without intervention.
Under anoxic conditions, which were routine at the sediment layer of the Slab Lab due to years of heavy organic loading, that phosphorus becomes chemically soluble. It doesn't matter what you do at the surface. If the sediment keeps releasing nutrients from below, the cycle never breaks. This is internal loading, and it's the reason so many ponds with chronic algae problems never improve no matter how many treatments are applied.
With the data in hand, Natural Waterscapes built a comprehensive reset plan. The math was straightforward: at a known rate of 1.3 gallons of MetaFloc per pound of phosphorus removed, the team calculated a reset dose of 5 totes, approximately 1,375 gallons, of the biological phosphorus binder. They also planned applications of MuckBiotics to begin breaking down the organic sludge at the bottom, installation of new surface aerators to keep the water column mixed and the sediment-water interface oxygenated, and deployment of a real-time water quality monitoring buoy to track conditions around the clock.
Jon worked behind the scenes coordinating equipment and logistics. The team assembled a crew that included Patrick, an aquatic biologist who specializes in invertebrate ecology and plankton analysis, and Chad, who would handle the heavy equipment work. Multiple industry partners were brought in to contribute expertise and resources. This wasn't going to be one company's effort. It was going to be a collaborative, data-driven reset of an entire ecosystem.
On September 30, 2025, the full team arrived in Alabama. The Reset was about to begin.
Standard water tests often miss the "legacy load" of nutrients trapped in pond sediments. That's why the team performed a sediment phosphorus fractionation, a test that quantifies how much reactive phosphorus is stored in the muck and how readily it can be released. Think of the sediment as a bank account that's been accumulating phosphorus deposits for years. Under the right conditions (low dissolved oxygen, warm temperatures, high pH) those deposits become soluble again, flooding the water column with algal fuel. This is internal loading, and it's the reason many ponds with chronic algae problems never improve no matter what surface treatments are applied. The phosphorus engine is running from below, and until you address it, the cycle never breaks.
The full team descended on the Slab Lab at the end of September. Heather led the operation. Chad was there to run the water quality tests and apply treatments. Jon assembled and deployed a real-time water quality buoy from the dock, giving the team 24/7 data on dissolved oxygen and temperature at multiple depths from that point forward.
The cyanobacteria was still thriving. Phormidium was rising from the bottom in dark, almost black clumps that floated at the surface. "It's really common for people to think that's string algae," Heather pointed out. "But look at it. It's so much darker. If you see stuff like that in a pond, it's probably not algae. It's cyanobacteria. And that can actually be just as toxic as the stuff that makes this water green."
Meanwhile, Chad and Heather loaded the boat with six 30-pound bags of MuckBiotics and began broadcasting them across the entire pond. Unlike liquid bacteria that disperses everywhere, pellets have a concentrated area of influence, so getting even distribution throughout the water matters. Chad distributed the pellets while Heather drove the boat, working to cover all five acres as evenly as possible.
By the end of Day 1, the buoy was transmitting, the sediment samples were on ice, and the MuckBiotics were sinking into the sludge layer to begin their work. The team regrouped that evening to plan the main event: MetaFloc.
Day 2 was the main event. Patrick arrived to help coordinate the Metafloc application. Five totes of MetaFloc, each holding 275 gallons, were staged and ready to go. The team ran a trash pump with suction lines dropped into the totes, pumping MetaFloc into the propeller wash of the boat and the surface aerators to get rapid, even distribution across all five acres. They moved fast. As Patrick explained: "Once we start going, we want to try to get as much of the product out as soon as possible so we can have good even spread coverage." Patrick ran the pump. Jon drove the boat while Chad manned the high pressure hose applying the MetaFloc. Heather directed positioning from the dock and drone.
MetaFloc is a biological phosphorus binder that works through dual mechanisms. Its flocculant gently binds suspended solids and dissolved phosphorus in the water column, forming heavy clumps that settle to the bottom. Unlike aluminum sulfate (alum), which aggressively crashes pH and can devastate zooplankton populations, MetaFloc creates a "soft" biological floc that binds nutrients without sterilizing the water or harming the organisms the pond needs to recover. Once settled, the beneficial bacterial cultures in MetaFloc continue working at the sediment surface, binding phosphorus in the muck and making it biologically unavailable. The settled material effectively "caps" the sediment, sealing the legacy phosphorus load beneath a biological barrier.
The results were visible within hours. Shades of green began to change, the fluorescent neon dimming to darker green, then mustard yellow, as the floc started binding the suspended particles and pulling them to the bottom. As Patrick put it: "It's not like algaecides where you're just kicking the can down the road or mowing the grass. This is changing the entire ecosystem for the better."
By the end of the day, the Slab Lab was visibly transformed. Sarah was seeing things she hadn't seen in years: rock piles, submerged habitat, even a feeder that had sunk years ago. Dennis stood on the dock and watched the water clear in real time. "With what Natural Waterscapes has brought to the table," he said, "their partnership with us has made all the difference in the world."
Aluminum sulfate (alum) is the traditional go-to for phosphorus removal in lakes, and it works, but at a cost. Alum treatments can crash water pH, which is devastating to zooplankton, the microscopic animals that form the critical link between algae and fish in the food web. In a pond where the entire goal is to rebuild that food web from the ground up, using a treatment that kills the organisms you're trying to cultivate is counterproductive. MetaFloc's biological approach achieves the same phosphorus binding without pH impacts, without water use restrictions, and with the added benefit of continued bacterial activity at the sediment surface, something chemical treatments simply cannot provide.
Heather was up early on Day 3, pulling surface and bottom water samples to compare against the readings taken before the MetaFloc application. Each test kit had to sit for 10 minutes before running. The team gathered around and waited.
Surface phosphate before the reset: 1.3 mg/L. This morning: 0.02 mg/L. A 98% reduction in 24 hours.
Bottom phosphate dropped from 0.16 to 0.05 mg/L, confirming that the MetaFloc had successfully settled through the water column and sealed the benthic layer. The sediment cap was holding. "The bottom sample is actually the more important one," Heather explained. "It tells us whether the sediment cap is doing its job. And it is."
Then came the visibility measurements.
The team measured 136 centimeters of clarity, just over 5 feet 4 inches. Heather turned to the camera with a grin: "I'm 5'4". So that's a great indicator." From 17 inches of pea soup to seeing the bottom of the pond. You could make out muck pellets on the bottom with floc settled on top of them, nearly burying them, less than 24 hours after the MetaFloc application.
But the moment that defined Day 3 wasn't in the test results. It was Sarah walking the banks of the Slab Lab that morning, seeing her pond for the first time with clear water. Seeing the bottom where her fish had lived, where they had spawned, where they had spent their days.
This is the moment that separates a real intervention from a cosmetic one. Plenty of products can make water look clear temporarily. The question is always what's happening beneath the surface. The lab data confirmed that MetaFloc wasn't just clearing the water. It was fundamentally changing the nutrient dynamics of the entire pond, from the surface to the sediment floor. And the woman who built this fishery could finally see it with her own eyes.
Before and after the MetaFloc application at the Slab Lab. 98% phosphorus reduction in 24 hours.
Orthophosphate (also called soluble reactive phosphorus, or SRP) is the form of phosphorus immediately available to algae. At 1.3 mg/L, the Slab Lab was running at more than 26 times higher than optimal levels for a healthy fishery. But the surface measurement alone doesn't tell the whole story. The bottom phosphate reading is equally important. A drop from 0.16 to 0.05 mg/L at the sediment-water interface means the MetaFloc successfully settled through the water column and formed a barrier over the legacy phosphorus stored in the muck. Without that cap, the 1,000+ pounds of phosphorus in the sediment would have continued cycling back into the water indefinitely, fueling bloom after bloom regardless of any surface treatment.
Water chemistry, depth, oxygen, sediment — the Slab Lab reset worked because we knew the numbers. MyPond is the free app we use to map a pond, track water quality, and turn readings into a clear plan.
Know Your Pond — Start Free → Free for up to 3 ponds · No credit card requiredDuring the reset week, two Kasco 3-horsepower surface aerators were assembled and installed at strategic locations across the pond, positioned with drone guidance from above. Their job is straightforward but critical: continuously mix the water column and force oxygen down to the sediment layer, keeping the bottom oxygenated so toxic gases and nutrients stay locked in the muck rather than accumulating and releasing during a storm event. The real-time water quality buoy confirmed the results immediately. Dissolved oxygen levels stabilized from top to bottom, day and night, eliminating the dangerous swings that had plagued the Slab Lab for years.
Six weeks post-reset, the team returned in November to conduct a full biological assessment. The question was no longer whether the water chemistry had improved. The question was whether the living systems were responding.
They were.
Patrick started with the benthic invertebrate community in the spawning areas, filtering sediment samples through a 500-micron sieve. Before the reset, the bottom was dominated by small oligochaete worms, pollution-tolerant indicators of low oxygen and high nutrient loads. Now the samples were full of chironomids (blood midges), and critically, the size class had increased dramatically. "That is so much bigger and better than what we had before," Patrick said, holding a specimen under the lens. "Before, there were no big ones. Zero. It was all really small worms. Now we're seeing this transition: bigger size classes, better composition." The target is 50 to 60 percent chironomids in the community, with mayflies and dragonflies expected to return as the sediment continues to recover over the coming seasons.
Then came the zooplankton. Patrick deployed a Wisconsin plankton net, an 80-micron mesh with a high-efficiency cone, towed vertically through the water column to capture 150 liters of composite sample. When the net came up, the team could see the zooplankton with the naked eye: clouds of Daphnia, Copepods, all large-bodied, all rich in lipids and essential fatty acids.
"I can tell you right now we're well above our thresholds," Patrick said, holding up the concentrated sample jar. "That is only 150 liters. Look at that." The sample looked like milk, thick and alive. Sarah took one look and the moment hit her. "Are you getting emotional over zooplankton?" someone asked. "Yeah," she said. "It's your babies."
And the phytoplankton told the most dramatic story of all. Lab analysis of cell counts showed the transformation in hard numbers: the pond had started with over 535,000 cyanobacteria cells per milliliter. Six weeks post-reset: 4,500 total cells per milliliter. Cyanobacteria: zero. The entire community had shifted to beneficial green algae and diatoms, species rich in the essential fatty acids that zooplankton need and that ultimately grow trophy fish. As Patrick put it: "Eating cyanobacteria is so nutritionally poor. It's like the iceberg lettuce of the pond world. Now we've got the good stuff."
The difference between a cyanobacteria-dominated pond and a diatom-dominated pond isn't cosmetic. It's the difference between a food web that works and one that doesn't. Cyanobacteria lack the essential fatty acids (PUFAs) and sterols that zooplankton need to survive and reproduce. While zooplankton can technically consume some cyanobacteria, the nutritional value is negligible, and large colonies of Microcystis are also physically too large for most zooplankton to ingest. The result is a biological dead end: energy from the sun gets trapped in toxic scum, dies, sinks, becomes muck, releases more nutrients, and starts the cycle over. Meanwhile, the dense bloom blocks sunlight from reaching the bottom, smothering benthic habitat and suppressing the invertebrate community that fish depend on.
Diatoms and green algae, by contrast, are the right size, the right nutrition, and the right energy package. When they dominate the phytoplankton community, zooplankton thrive, and that energy flows efficiently up to the fish. The shift from over 535,000 cyanobacteria cells per milliliter to zero is the single most important indicator that this ecosystem is now functioning as it should.
The long-term goal for the benthic community is the return of sensitive indicator species like mayflies (Ephemeroptera) and dragonflies (Odonata), which require clean sediment and stable oxygen levels. Their presence would confirm that the sediment recovery is complete, a process that typically takes one to two full seasons.
Daphnia at 10x magnification from the Slab Lab. The return of zooplankton confirms the food web is firing. Image by Natural Waterscapes.
The monitoring continues. The real-time water quality buoy tracks dissolved oxygen around the clock, and the team monitors the spread between daytime highs and nighttime lows in dissolved oxygen. A widening gap could signal an algae bloom building momentum and require additional treatments. Each water sample, each microscopy session, each data point from the buoy adds another chapter to a story that is still being written.
Five months after the reset, Sarah Parvin and her father Dennis sat down on camera for the first time to share the full backstory of the pond that started it all. From the first shovel of dirt in 1995 to producing 14-pound bass and later some of the largest coppernose bluegill in the country, the Slab Lab has been the centerpiece of decades of passion, experimentation, and family memories.
Dennis walked viewers through the original construction: the channels, the riprap, the sand, the pea gravel — hand-placed structure designed to grow giants. Sarah talked about the devastating 2018 die-off that shifted the mission from bass to trophy bluegill, and why this latest reset isn't just about water chemistry. It's about protecting something deeply personal. This episode gives the entire comeback its proper emotional foundation.
The management philosophy has fundamentally changed coming out of this reset. The Slab Lab is no longer managed for "color." It's managed for constituents. Every decision is driven by data: what's in the water, what's in the sediment, what's growing in the phytoplankton community, and what's eating it. Two Kasco surface aerators now keep the entire water column mixed and the sediment-water interface oxygenated. The real-time water quality buoy watches it all in real time. As Sarah put it from the beginning: "Awareness precedes change. We've got to know what we're dealing with." Now they do.
After months of chemistry work, biology monitoring, and food-web building, the moment everyone had been waiting for finally arrived. In Episode 10, Sarah Parvin and the Natural Waterscapes team stocked the foundation fish that will build the next generation of trophy coppernose bluegill at the Slab Lab.
Five months post-reset, the numbers told a clear story: the water was clean, the food web was thriving with zooplankton and invertebrates, oxygen levels were stable, and nutrients were under control. For the first time in years, the pond was ready to support elite fish growth from the ground up. Before the reset, the Slab Lab produced giant fish even under difficult conditions — overcrowding, predator pressure, unstable water quality. Now, with those limitations removed, the question isn't if trophy fish will grow here. It's how fast.
The stocking strategy was deliberate and intentional. With water quality so exceptional, the team chose to stock fewer fish than a standard stocking protocol would call for. Higher survival rates in pristine water mean recruits per acre will be greater than usual — overstocking at the outset would just create the competition pressure the reset was designed to eliminate. The strategy is patient and precise: stock quality, not quantity, and let the food web do its work.
Conventional stocking wisdom maximizes initial fish numbers, but in an ecosystem reset, the calculus is different. When water quality is pristine and dissolved oxygen is stable 24/7, survival rates of stocked fingerlings are dramatically higher than in stressed systems. Stocking at standard rates in exceptional water can quickly lead to the same overcrowding and competitive stress that contributed to the original fish kill. By stocking conservatively and allowing the abundant food web — loaded with Daphnia, copepods, and benthic invertebrates — to support the fish that are present, each individual fish has access to more calories per day, resulting in faster individual growth rates. The trophy fishery goal is measured in pounds-per-fish, not fish-per-acre.
One of the most overlooked pillars of a trophy fishery isn't in the water column — it's in the mud. Episode 11 took a hard look at the benthic invertebrate community, the organisms living in and just above the sediment that form a critical link in the food chain from muck to mouth. Following the catastrophic fish kill, the bottom of the Slab Lab was biologically broken: low diversity, poor size structure, and limited energy transfer. No fuel for fish growth.
By March 2026, the data was showing real, measurable movement. Explosive increases in midge larvae density were confirmed, along with meaningful shifts in size class — critically, the prey-size midge larvae that bluegill actually eat were now present in abundance. Early signs of diversity recovery were emerging too, with new species beginning to recolonize the stabilized sediment. This isn't just a food source. It's biological proof that the sediment conditions have fundamentally changed.
The long-term target for the benthic community remains 50–60% chironomids by composition, with the gradual return of sensitive indicator species like mayflies and dragonflies expected to confirm full sediment recovery over the coming seasons. The Slab Lab is tracking ahead of schedule.
The biggest shift at the Slab Lab right now is happening at a level you can't even see. Episode 12 revealed one of the most significant milestones since the reset: a full zooplankton biomass report showing that the pond's recovery isn't just holding — it's accelerating. Biomass is surging. Diversity is expanding. And for the first time since the reset, the system is rebuilding itself in a way that supports long-term fish growth, not just survival.
The data doesn't lie. Large-bodied zooplankton — Daphnia, copepods, cladocerans — are now thriving in numbers well above the 250 micrograms per liter threshold the team uses as a performance baseline. These energy-rich organisms form the direct bridge between the phytoplankton bloom and the fish above them. And perhaps most importantly: a strong zooplankton community at this stage means the pond is preparing itself for its first spawning event since the fish kill. Higher survival rates of fry. More recruits. More future slabs.
The timing of a strong zooplankton bloom relative to spawn timing is one of the most important factors in juvenile fish survival. Newly hatched bluegill fry require zooplankton as their first food — they are too small to consume anything else effectively in the first days of life. When zooplankton biomass is high and composed of appropriately sized prey during spawn season, fry survival rates can be dramatically higher than in systems where the timing is off or the biomass is low. This is called the "match-mismatch" hypothesis in fisheries ecology, and the Slab Lab is setting up for a strong match heading into its first spawn since the reset.
Episode 13 got hands-on with one of the most important tools in a serious trophy fishery program: individual fish tracking via pit tags. The team began inserting nano PIT tags (passive integrated transponder tags, approximately 8mm) at the base of the dorsal fin on coppernose bluegill, giving each fish a permanent, scannable ID. The goal is a long-term dataset: every tagged fish becomes a data point that connects a specific individual's length, weight, and relative weight at a known date to every future recapture. Over months and years, this data tells the story of how fast fish are growing, whether the food web is delivering results, and when the pond produces its first record-class fish.
The early numbers were encouraging. Fish caught hook-and-line for assessment were averaging a relative weight of 145% — a strong indicator that the food web is delivering more than enough nutrition and that growth rates are on track for trophy-class fish. Fish at 145% relative weight are, put simply, fat. They are eating well, growing fast, and not competing excessively for forage. "That tells me that those fish are getting in more than enough food and that they are eating what's available to them," said the lead biologist during filming. "And keep in mind, these fish are not on pellet feed right now. They are doing that entirely through the food web."
Relative weight data also revealed something important about the management decision to under-stock at the outset. With pristine water quality and low fish density, mortality rates have been significantly lower than historical norms. Before the reset, stress-related losses from disease, overcrowding, and water quality spikes were estimated at 20–30% annually. At this point in the recovery, the fish being sampled show no visible stress indicators: clean scales, clear eyes, healthy body condition. The reset has changed not just the water, but the quality of life for every fish in it.
Relative weight (Wr) is calculated by comparing an individual fish's actual weight to the expected weight for a fish of that length based on published species-specific standards. A Wr of 100% means the fish weighs exactly what the average fish of that length should weigh. A Wr above 100% means the fish is heavier — indicating good body condition and adequate forage. At 145%, the Slab Lab's coppernose are well above average condition, which confirms that forage density and quality are high. For a trophy fishery manager, consistently high relative weights across the population are one of the strongest early signals that the food web is firing properly and that exceptional individual growth rates are likely to follow.
The latest chapter in the Slab Lab story adds an entirely new layer of habitat — literally. In Episode 14, Sarah Parvin, Jon Klotz, Heather Newhart, and the Natural Waterscapes team assembled, planted, launched, and anchored the first floating wetland islands at the Slab Lab. These aren't decorative features. Their submerged root systems create shelter, feeding opportunities, and biological activity that support everything from microscopic zooplankton to the trophy coppernose bluegill being grown here.
Floating treatment wetlands work through multiple mechanisms simultaneously. The root systems host dense colonies of beneficial microbes that continue breaking down organic material and cycling nutrients. They provide physical refuge — critical structure in an open-water pond — that bluegill instinctively use for feeding and resting. And they create yet another layer of biological habitat that the pond's food web can colonize and expand into, compounding the recovery work that's been underway since October 2025. The islands were designed in partnership with floatingwetlands.com.
The Slab Lab reset is now eight months in. The water quality has been stabilized. The sediment has been capped. The food web is firing at well above baseline. Fish are tagged, growing, and fat. And now the physical habitat is being deliberately layered on top of it all. The question isn't if the Slab Lab produces a world-record coppernose bluegill. It's when.
Just when the recovery looked locked in, the Slab Lab threw a curveball. An exploding crawfish population began undoing months of progress — burrowing through and disturbing the years of nutrient-rich sediment the reset had worked so hard to cap, and in the process reintroducing dormant cyanobacteria back into the water column. It was a stark reminder that a pond is a living system, and no restoration is ever truly "finished."
True to the Slab Lab philosophy, the response was driven by data, not guesswork. Rather than starting over, the team made a targeted MetaFloc maintenance application to re-bind the freshly disturbed phosphorus, while preparing to introduce largemouth bass to help bring the crawfish numbers back into balance biologically. This episode is also a case study in why sediment testing has become one of the most important tools in modern pond management — water samples only tell part of the story, because the real nutrient reservoir is often hiding beneath the surface.
Crawfish are ecosystem engineers. In high densities, their constant burrowing and foraging physically reworks the top layer of pond sediment — the exact layer a phosphorus binder like MetaFloc is designed to seal. When that cap is disturbed, legacy phosphorus that had been locked away can re-enter the water column, and dormant cyanobacteria resting in the sediment can be resuspended and reactivated. This is why the Slab Lab's response paired a chemical re-treatment (a maintenance MetaFloc dose to re-bind the freed phosphorus) with a biological control (introducing largemouth bass as a natural predator to reduce crawfish density). It is a textbook example of integrated pond management: treat the symptom and the root cause at the same time.
With the problem identified, it was time to act. The team deployed professional crawfish traps across the pond and got to work quantifying the scale of the invasion. Using CPUE (catch-per-unit-effort) sampling — the same standardized method fisheries biologists use to estimate fish populations — they translated trap counts into a real density estimate, turning a gut-feeling "there are a lot of crawfish" into hard, trackable data.
The numbers confirmed it: thousands of wild crawfish had overtaken the pond, competing with the bluegill for the same forage base and disrupting the habitat balance the reset had established. Over the course of the effort, more than 100 traps were deployed to bring the population back under control. And because these were clean, wild crawfish harvested from restored water, the day ended the only way a Louisiana-style harvest should — with a proper Cajun crawfish boil, done in partnership with KFRED.
Want the full recipe? In a companion video, the team walks through the entire Cajun boil start to finish — how to clean, season, boil, and peel wild pond crawfish with corn, potatoes, and bold Louisiana seasoning — while explaining why an overpopulated crawfish colony can quietly reshape a fishery below the surface.
One year after a catastrophic fish kill wiped out the original Slab Lab, Sarah Parvin and the Natural Waterscapes team sat down to revisit the full arc — the science, the setbacks, and the work behind rebuilding a world-class trophy coppernose bluegill fishery from zero. The transformation has been dramatic. Water clarity jumped to 64 inches within 24 hours of the original reset. Copepods, zooplankton, chironomids, and fathead minnows returned in force, rebuilding the natural food supply the fish depend on. And even while many of the fish largely ignored supplemental feed, the pond produced an average relative weight of 132% — elite body condition built almost entirely on the recovered food web.
But the year was anything but smooth. The extreme crawfish population disturbed the pond bottom and reversed a chunk of the reset's progress before more than 100 traps brought the density back under control. With that fire put out, the team could refocus on what the Slab Lab is really about: real-time dissolved oxygen monitoring, managing daily oxygen swings and bloom density, and holding the delicate balance between fish density, forage availability, water quality, and habitat as the fishery enters year two. One year after losing everything, the Slab Lab is once again producing trophy-size bluegill.
Prefer the unscripted version? On July 20, Sarah, Heather, and Jon hosted a nearly hour-long live check-in to hit the highlights of the first year in real time — a looser, wider-ranging conversation covering the same milestones, the crawfish setback, and what comes next. The full live recording is embedded below.
Follow along as new chapters are added. This page will be updated regularly as the Slab Lab continues its journey from reset to record.
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