There are a few types but in only going to write down the main types you'd find in any retail aquarium.
Bristlenose Catfish
Origin: South America
Size: they start at around 4cm and can reach very big sizes if kept in a big tank but usually they'll only grow to be about 11cm
Temperature: 23' - 29' degrees Celsius is best
Water Conditions: soft to acidic with a pH level of around 6 - 7
Comments: A moderately easy fish to keep as long as there's heaps of algae build up and you drop in a few algae chips a week as extra just in case he doesn't get enough algae from the surroundings. A great community fish with either large or small fish, they have been known to breed in the hobby aquarium as pure luck and the male will tend to look after the eggs he is recognizable by the bristles on the face. The most disappointing thing about these magnificent fish is they are nocturnal so you'll barely ever see them.
Sucking Catfish
Origin: South America
Size: 3cm
Temperature: 23' - 29' degrees Celsius
Water Conditions: soft to acidic with a pH of around 6 - 7
Comments: A great community dwelling fish they'll eat all the algae build up in the tank in a small group and are active during the day and night. feeding them on algae chips as well is a good idea, if they grow big they will cling to fish such as angels and discuss fish and try to clean them of algae and in the process hurt them giving them a wound which will be open for infections and also they will tend to eat whole into delicate plants such as the Amazon sword.
