CrashingWaves
Fish Crazy
Competition for food and space is probably the main problem I would be guessing. The minimum size tank to keep clown loaches in would be 55 gallons. Even then, many loach guru's would argue that even that is too small. Clown loaches tend to grow extremely slowly once they get to be about 5 or 6 inches long. I personally don't have a problem with somebody keeping clown loaches in a 55 gallon tank.
God Bless,
Joshua
God Bless,
Joshua