Fall Fish Growth

By Bob Lusk

With much of Summer, 2025 in the rearview mirror, but before the first true wisp of fall, several of Nature’s truths are about to play out.

Each season stands on its own merit. Think about it…spring time, trees bud, flowers bloom, plants thrive, and fish spawn. Summertime—nature pushes, fish recover from reproducing, plants grow toward this year’s maturity. When your water gets hot, like it’s been for the better part of two or three months, even warm water fish slow down. Being cold-blooded, their metabolism actually slows when the water is hot.

Fish have prime operating temperatures. Remember that. Different species metabolize and grow within their own zones.

But wait, there’s more. As the temperature begins to mitigate and drop, and photoperiod silently shifts, your fish sense the water is becoming their oasis once again. By now, your food chain, if properly managed, is striving toward peak volume. Baitfish have reproduced, some babies have surely been eaten (most of them, actually), the rest are growing, and your fishery is producing some healthy nuggets of food for your predator fish.

By nature’s design, and by your nudges, your food chain reaches its crescendo about October. Carrying capacity of your pond is approaching max, the standing crop is at a peak, and your predator fish are just now reaching their engine’s peak operating temperature.

Now is when your game fish will grow the fastest of all year. They have to. Winter will wrap its frigid arms around your pond before long and your fish have a limited time window to gain as much weight as they can to prepare. Part of nature’s mission is for your fish to gain some fat, too.

Whether a pond grows walleye, Largemouth bass, smallies, Tiger muskies, crappie, yellow perch…whatever, those fish can better survive winter if they gain weight and build up some fat stores.

Peeling back that layer, understand that much of your natural food chain will be consumed this fall, and pretty much the rest of it will go down the gullet of predator fish over the winter months. If your game fish run out of food, they have no choice but metabolize their own tissues. That’s where the fat comes in. If they have enough fat stores, they don’t metabolize much flesh.

Why is that important, you are hopefully asking?

If a game fish metabolizes its flesh, it has to regain that weight before it grows again next year. Maybe it can, maybe it won’t. If it metabolizes fat and has enough forage fish to make it through winter, your fish have a big jump start into 2026.

That’s your formula for the best-of-the-best to roll toward trophy status.

Okay, pondmeisters, what can you do to set the stage for all this stuff to come together?

Plenty.

If your water has been happy all year, and you’ve made sure the different trophic levels of the food chain had what they needed, fertility for a healthy bloom, great fish food to supplement those fish which needed it for great growth and reproduction, and your baitfish have reproduced like little underwater rabbits, you’ve done your part…for now.

For pondmeisters in the Midwest and North, your focus is now dialed into managing water quality to keep things healthy under ice. If aquatic vegetation is excessive, consider raking it out to eliminate the risk of dead plants decomposing over winter and compromising water quality…consuming too much oxygen and injecting gases that can’t escape because of ice. Do what you can to prevent winterkill. If plants aren’t an issue right now, feed your fish, whether by stocking some fathead minnows, shiners, regionally available baitfish, even bluegills, or giving your fishery a nudge with a high-quality fish food such as Purina’s AquaMax Sport Fish products.

For those in the south, southeast, and the southwest, feed your fish. If you are confident your baitfish numbers are low, supplement them. Call nearby hatcheries and see what’s available that fits your budget and your fishery. Feed a high-quality fish food to give your fish all they need to grow as needed before winter sets in.

For everyone, cull the underperformers this fall. Take out those fish which don’t score well. How to judge? Study their body condition. If your game fish score less than 90% relative weight for their species, introduce them to peanut oil at 350-degrees, after dredging them in Louisiana Fish Fry, a batter available at most supermarkets.

What else can you do? Get your water into the best shape possible for winter. One thing I preach is to use your bottom-diffused aeration system on a timer, if your water temperate exceeds 83 degrees. Most warmwater fish don’t appreciate water warmer than that. Since bottom-diffused aeration creates an autonomous water environment top to bottom, fish can’t escape to a thermal refuge…since one doesn’t exist. But once water temperature drops below 80 degrees, run that system full time—until your water hits 55 degrees. Then, consider shutting it off.

Here's why—when the water drops to 55 degrees, its affinity for oxygen has increased as your fishes’ metabolism has slowed. You’re safe at that point to turn off the aeration system, unless you have a different compelling reason to keep it running.

There you have it. Keeping water healthy, to prepare for winter, feeding your fish so they can gain weight to thrive during the winter, culling the overburden of fish that need to be harvested. These topics are your backbone for thought for a fun fishing bursting with potential for 2026.