The rivers of Trinidad are home to six very distinctive types of catfish. These include armoured catfish such as the leopard-spotted ‘teta’ (Hypostomus robinii), the enigmatic ‘cascadu’ (Hoplosternum littorale) and the popular aquarium fish ‘pui pui’ (Corydoras aeneus). All tend to be bottom-dwellers and are grouped together as ‘cat’ fish on account of their barbels, which are sensory ‘whisker-like’ structures on their faces used to locate food. In Trinidad the fish most commonly referred to by the name ‘catfish’ is Rhamdia quelen, which unlike the species listed above, is silvery, unarmoured and scale-less.
Like many catfish species, Rhamdia possess mildly venomous spiny rays on their pectoral and dorsal fins, which are used for defence against larger predatory fish. The barbels on either side of their face help them locate food in dark or murky waters, such as their preferred prey of small fish. However, their varied omnivorous diet also includes insects, zooplankton, plant matter and crustaceans.