Otocinclus are some of the smallest species of suckermouth catfish and certainly the only ones likely to be seen in numbers in the average store.
 
Peaceful by nature, these fish tend to do best in large groups and have the added benefit of helping to control certain types of algae whilst leaving precious plant-life alone. They do, however, have a reputation for being rather delicate, so must only be considered for mature aquaria rich in algae and biofilm with a good level of oxygenation. If acclimatised carefully to such tanks these herbivores should fare well and can be expected to live upwards of 6 years. Their diminutive size means that they are one of the better choices for smaller aquaria. The tank itself should be decorated with a dark substrate, incorporating dense areas of planting and shady hidey holes amongst bogwood and rocky caves. Bright lighting will encourage abundant algal growth, which will provide some nourishment for the fish (but should not be solely relied upon). Soft-neutral conditions are recommended for Otocinclus, as are areas of moderate current. Small, peaceful tankmates such some members of the Tetra, Pencilfish and Corydoras families would be suitable. Otocinclus can be sensitive to chemical treatments and nitrogenous wastes, such as those which fuel algae outbreaks. Ensure that small partial water changes are carried out at least once or twice per week.