When maintaining a freshwater tank, algae growth should be kept at a minimum. Even if you maintain minimal levels of nitrogen and phosphate levels, algae eaters make a great clean-up crew. You don’t have to go with the typical Plecostomus, as there are many species of algae eaters that will keep your rocks, decorations, plants and glass clean.
Shrimps are algae scavengers, making them great algae eaters. They are generally quite peaceful but can become aggressive if they cannot find enough food. The amano shrimp is one of the most common algae-eating shrimps available. This shrimp will clean up dead plants and leftover food, which will help your tank's chemical balance and in turn reduce algae. It will also eat most types of algae, except green spot and blue-green algae. You do want to be careful putting amano shrimp in aquariums with larger fish, such as cichlids, that will eat the shrimp.
Snails reproduce very quickly and may be eaten by larger fish, such as loaches and cichlids, but they make great algae eaters. The ramshorn snail will rid your freshwater tank of algae, as well as eat dead plants, leftover food and fish eggs. Zebra nerite snails have beautiful patterns on their shells, but their beauty is not the only benefit to your tank; these snails will eat the hard-to-get algae like green spot algae and carpet-like green beard algae. Malaysian trumpet snails are ideal for planted freshwater tanks because they will eat the algae, dead plant material and leftover food, but they will not eat your plants.
Catfish are excellent cleanup fish. The otocinclus catfish is one of the more popular catfish species sold as algae eaters; they will devour the algae, especially what is in between foliage. They are a dwarf sucker-mouth catfish, only reaching about 4 to 5 inches, making them a nice option for small- to medium-size aquariums. The pleco species are bottom-feeding catfish that are great algae eaters. The bristlenose, hypostomus and farlowella plecos are all great algae-eating catfish species. The farlowella pleco, or twig catfish, is not as common as the bristlenose variety, which is actually a smaller catfish that is great for smaller freshwater tanks.
Loaches, Chinese algae eaters and common plecos are popular algae-feeding bottom feeders. Since dead plants and leftover food sinks to the bottom of your aquarium, you may want to consider a fish or two that will scavenge the substrate layer. There are many species of loaches; the clown loach is a common fish that is best kept in small groups. This fish will peck at the algae on the decorations and in the gravel. Chinese algae eaters can become aggressive and territorial as they age but are great at scraping the algae off rocks, driftwood, glass and plants. If you opt for the common plecostomus, which is great for cleaning the glass of your tank, you want to be careful as to what species you choose, as some reach 11 to 23 inches.
Mollies, guppies and platies are not the best algae-eating fish, but they will bite off and eat soft hair algae and some strand-like types of algae. Black mollies can be raised solely on an algae diet, eating fuzz algae and beard algae, but they are omnivores, surviving best on fish flakes. Live-bearing fish species can be an option for your freshwater aquarium, but you may want to consider adding another type of algae fish to your tank to help keep your tank clean and free of an algae overgrowth.