how big do sucker catfish get?

if you mean a common pleco, then about 18-24 inches and they are poop factories.

however there are more than 800 species of pleco that range from 3" adult size on up.
 
Unfortunately, common names are the bane of many an aquarist...as mentioned before, many plecs could be considered a "sucker catfish". As suggested above, the fish is likely a common pleco that will get huge and need heavy duty filtration and water changes. I love plecs and I try to have one in every tank that I can, if appropriate. The link to planet catfish mentioned above is a great website to explore.
 
Gumby131 said:
ok dont owrry think its a chinese algae eater,
can these be compadible with corys neons a juve. angel guppies and daniios


I wouldn't buy one of those, as they get older they will pick off your smaller fish.
I had one in my guppy/neon tank that got to be about 6 inches and he started picking off neons. Otto's may be a better choice.

Dave
 
AquariaCentral.com