PlanetCatfish.com

ok, so you know about my blue channel cats, i was wondering how fast they grow and essentially how big they get?

mine are around 3-3.5" each so how fast do they grow?

and are they like koi, do they release a horomone into the water that prevents them from growing any bigger when it reaches a certain concentration or is that just for koi?

The growth of channel cats is not linear. Growth is rapid the first two or three years, and then it begins to slow. You can expect your channel cat to reach a length of 35 cm (about 14") in about 5 years.
Maximum recorded size of a channel cat is nearly a meter (that would be um, about a little over 3').
Don't know about the hormonal thing, but I suspect it doesn't happen. Channel cats rarely live beyond 8 years in the wild.