Originally Posted by Aluyasha
Most Plecos (if that is what you mean by "suckerfish") grow to be very large, normally needing at least a 55 gallon. Also, plecos tend to become more aggressive the older and bigger they get. It is not surprising to hear a story about a Pleco holding down a fish and sucking it's scales off.
As with most catfish (pictus and the like). They will attack your fish once the lights go out and also most grow very large.
So as the others have said. It is important to know the type of Pleco/catfish.
Actually, most plecos are 6 inches max. And only the carnivorous species suck on slime coat. Oppurtinistic feeders like common plecos will eat anything. If it is a chinese algea eater it is also bad, as they love slime coat. A bulldog pleco would be fine because they grow to only two inches, but I dought it is a bulldog plec.