Many people in the aquarium hobby seek fish that will do a lot of the dirty work for them. While the desire to minimize the amount of cleaning one does around the aquarium is understandable, I would like to stress that no tropical fish will effectively replace a simple gravel vac, an algae pad, and a bit of elbow grease.
Still, many freshwater aquarium hobbyists choose to buy “cleaning” fish and/or snails only to find that many of them end up producing more waste then they consume!
The infamous Plecostomus – variously called “pleco,” “suckerfish,” or “algae-eater” – comes to mind. People often purchase baby Common Plecos only to find that their cute little suckerfish turned into a smelly, small-fish-eating, 1 foot (30 cm) giant just a few months down the road! Yes, these fish do produce more waste than they consume, and, no, I do not recommend that anyone gets one (unless it’s purely for ornamental value).
Fortunately, hobbyists who want to add bottom dwelling fish to their aquarium have an excellent alternative. The Cory Catfish (also known as the Cory Cat) is an excellent addition to most community aquariums.
The Cory Cats are bottom dwelling catfish that originate from South America. These extremely peaceful fish grow to only 2.5 inches (6.25 cm) to 3.5 inches (8.75 cm) in length, and more than a few species are available for the aquarium trade. In fact, it’s common to find variously colored and patterned Cory Cats at a single store. These fish are readily available.
Moreover, Cory Cats are actually pretty good at sucking up uneaten food from the bottom of the aquarium. Any food your other fish will miss, the Cory Cats will quickly consume, thus lessoning the amount of stress put on your biological filter following feeding time. Yes; Cory Cats are excellent bottom feeders.
Because of their specialized feeding behavior, I recommend adding Cory Cats (or any other bottom feeders for that matter) to your aquarium only after a few other fish have been added. Indeed, as I describe in Chapter Nine of The Kick-Ass Aquarium Book, bottom-feeding fish rely on the presence of other fish – sloppy eaters that provide scavengers with a continuous supply of food – for nutrition. If not enough fish are present in the aquarium, the Cory Cats’ diet must be supplemented with at least one of the foods described below.
I would like to mention again that, although the Cory Cats are wonderful scavengers which will reduce the amount of waste present in the home aquarium, no animal will replace the cleaning power of physical waste removal. Still, the Corys are wonderful little fishes, and are an excellent alternative to the monster mentioned at the top of the article.
Scientific Name: Corydoras spp. and Brochis spp.
Origin: South America
Water Temperature Range: 74-82 °F (23-28 °C)
Water pH Range: 6.0-7.0
Temperament: peaceful (like to live in small groups of 6 or more, though 2 specimens can be kept successfully)
Maximum Size: 2.5 to 3.5 inch (6.25 to 8.75 cm) depending on species
Minimum Tank Size: 10 U.S. gallons (28 liters), though, as I indicate in The Kick-Ass Aquarium Book, a larger aquarium size is strongly advisable.
Diet: bottom feeder – algae wafers, flake food, frozen brine shrimp, cyclops-eeze