Bottom feeders are fish that live and eat at the bottom of rivers, lakes or oceans. Many bottom feeders have mouths that point downward to make it easier for them to find food along the bottom of their habitat. Generally, aquarium bottom feeders are known for cleaning up the debris of other fish including algae.
Birchirs are oxygen-breathing bottom feeders that need to be able to surface for fresh air. They're nocturnal fish and prefer a habitat that resembles their natural environment like soft sand, lots of foliage and rocks to hide behind. Birchirs are predators and should not be in the same aquarium with smaller fish.
So named because of the feelers that resemble cat's whiskers around it's mouth, catfish are nocturnal scavengers. Catfish are beneficial additions to aquariums because they'll eat algae from the sides of the tank and eating any left over food particles. Catfish are social fish and do better in groups of four or more.
Loaches come in a variety of colourful options. They're aggressive when alone and do better when in a group of at last a half dozen. Loaches are scavenger fish and help keep aquariums clean.
Pufferfish, often called blowfish, are known for taking in large amounts of water very quickly, thus turning themselves into large balls. This defence makes them almost impervious to attack from other fish. Pufferfish eat mostly algae and invertebrates, although some eat mussels and shellfish.