Plecostomus fish, nicknamed plecos, sucker fish and suckermouth catfish, are usually classified or sold as “cleaner fish.” Many people do not realize just what “cleaner fish” means. It does not mean that plecostomus fish can eat fish feces. They ignore feces. But they will clean up any food left over from the other fish, will eat the corpses of dead fish and, most importantly, a large part of their diet is algae.
Older plecos tend not to be as diligent about cleaning algae off of the gravel as younger plecos, which are vigorous in cleaning just about ever inch of the tank. The older plecos will still clean the glass and decorations and spend the rest of the day hanging out in a favorite hiding spot.
Main Diet — Algae
Algae is normal in healthy freshwater for fish. A little bit of in a freshwater aquarium or pond will not harm the fish or any live plants. But algae grows quickly and it can soon get out of hand. Although many fish, including goldfish, will sometimes eat algae, they do not seem to relish it as much as the members of the plecostumus fish family.
Since plecos also grow quickly (the common plecostomus or Hypostomus plecostomus can grow up to two feet long), they usually need more algae than a normal healthy freshwater tank or pond can provide. They need their diet to be supplemented with sinking algae wafers. Each individual pleco will have his or her unique appetite. Some plecos will need a wafer daily while some only need a wafer two or three times a week. If the water is getting cloudy and you find yourself changing it more often, then consider cutting back on the wafers.
Meat Based Foods
But plecos do need to eat more than just algae in order to stay healthy. They do need protein and that means they need to eat meat. They enjoy frozen or freeze-dried bloodworms, fish-based fish flakes, sinking shrimp pellets, fresh shrimp that has not been battered or covered in spices. These can be given once or twice a week as a treat.
Some plecos do get a taste for the slime on the bodies of other fish. When hungry, the plecos will then begin to suck on its victim, which usually dies of injuries. But plecos need fish large enough and slow enough to latch onto. Some plecos just never get into the habit of fish-sucking. Fish-sucking plecos ideally should live alone or with fish far too small for them to latch onto.
Each pleco seems to have its own tastes. For example, several web sites have recommended giving canned green beans to plecos as a treat. This writer’s 8.5 inch long common plecostomus promptly ignores them. He also ignores fresh, cleaned lettuce but these are a hit with others of his species. Only leave a vegetable treat in the tank for a few hours. Remove any uneaten chunks or they will begin to rot.
Other vegetable treats said to be favored by plecos – especially young, growing and ravenous plecos – are canned and fresh peas; blanched zucchini; fresh cucumber and fresh green beans. Be sure to wash any fresh vegetables before giving them to fish, just in case any pesticides are on them. When in doubt, do not feed. Plecos are most active at night so it may be best to feed the treat at night or dusk.
“Freshwater Aquariums For Dummies, Second Edition.” Maddy Hargrove & Mic Hargrove. Wiley Publishing; 2006.
Aquatic Community. “Pleco.” http://www.aquaticcommunity.com/catfish/pleco.php
Aqualand. “Overview of the available plecostomus species with pictures.” http://aqualandpetsplus.com/Catfish,%20Plecoctomus.htm