When you feel that quick bite on the other end, you know you’re hooked up to a catfish. Now what? Is this big enough for the livewell, or is it back in the drink for us? How do you decide within a split second. The very judgement call that separates biology from the sport and how knowing the fish’s weight-to-length relationship can make such a clear decision different than a fuzzy “it was kinda big”.
Three species represent transition between fingerling size and trophy size. There is no doubt that channel catfish can be caught by many anglers since this fish inhabit almost any freshwater system found throughout North America. They possess a long body with a slightly forked tail, which means they aren’t going to pack on a bunch of pounds unless they’re pretty darn big. In many states, the legal size limit for a channel cat is around 12 inches, which usually weigh about one-half pound. That’s a nice bite but it won’t make you test out your drag setting.
How to Know Your Catfish Size Quickly
Once you exceed twenty inches, you’re getting into some fun stuff. The weight gain greatly increase. The battle will be memorable, making the wait worthwhile.
Potential: Unlike other fish, blue catfish is more of an exception when it comes to size and potential. Blue cats tend to inhabit mainstem reservoirs or large rivers, grow wide (not long) and accumulate serious pounds per inch. You can see from the graph above, they don’t get big quickly. By the time a blue cat gets to fifty inches in length, he’s easily over forty pounds, if not more.
This is why conserving these fish are so important. To become such a trophy, a forty pound blue cat had to survive more than a decade and a half of environmental changes, anglers, and predators. When we release them, we know all those hard earned years would of go toward contributing something else to our sport, not sitting on a grill.
The odd body shape of flathead catfish make estimating sizes even harder. They have wide heads and square tails. They like rocks and deep holes and don’t spend as much time out in the open. A twenty six inch fish will probably be guessed by using a simple calculator to be about fifteen pounds. But a healthy flathead can tip the scales upwards of seven or eight additional pounds. This is significant if you’re thinking about netting it and wanting to know if your net is strong enough not to tear under the strain.
If you’re familiar with these mathematical tricks, you don’t need a digital scale to estimate your catchs weight in the field. The “length-only” method uses only length measurements. It multiplies the total length by itself twice (i.e., cubed) and divides by a constant specific to each species, which yields an impressively accurate ballpark number. Because of their thick bodies, heavier-bodied flatheads requires a change of this divisor downward.
Knowing this quick formula gives anglers something to base their expectations on prior to removing the fish from the water so they can get the right equipment ready for catching and weighing it without rushing things. Big ones is worth their weight in gold because they also take decades to reach maturity. That being said, proper handling of big catfish are equally critical.
Always hold them horizontal in the water when supporting them. Holding a big bass by the mouth vertically can cause permanent damage to your jaw joint and it can be even worse on a big one (i.e., more than ten pounds). Circle hooks decreases the risk of gut hooking. Minimizing the amount of time they spend out of the water improves survival rates upon release. In warm water situations, they gets stressed out very fast so quick and gentle handling is not negotiable.
This knowledge impacts every fishing trip. When you know how they grow up, you begin considering age, habitat and the conservation impact before blindly going for a bite. It doesn’t matter if you are looking for a record breaking monster or a quick meal, this information improve the experience. So when you get the big one on the end of the line, you already kind of know what it is. This transforms an ordinary catch into a story you can tell others long after the fish has swum off.