Why do catfish get so big?

You might be wondering: Everyone gets full sometime, so how can they keep up such a heavy feeding schedule? Although mature Mekong giant catfish grow less slowly after their initial spurt, they still love to chow down and they can accommodate this avid appetite with an expandable abdomen and digestive tract. read more

At maturity, catfish come in a wide range of sizes. Some little guys can be as tiny as 1 1/2 to 2 inches long (that's about 4 to 5 centimeters) [source: Encyclopedia Britannica]. Others can grow to absolutely mammoth sizes; they're definitely contenders for the title of world's largest freshwater fish. read more

Fish technically don't stop growing, so to speak. They grow as large as their habit will allow them to grow pretty much. The goldfish for example will stay relatively small in a 40 gallon tank, but put it in a 1000 gallon tank with more food, and it will grow larger. Same goes for the catfish. read more