The toothless Garra Rufa can feed on the exfoliating epidermis of people suffering from psoriasis, for example. Treatment involves submerging the limbs, sometimes even the entire body, in an aquarium with these fish. One treatment usually takes up to 30 minutes and several hundred fish are needed. Opponents of ichthyotherapy draw attention to the risk of waterborne diseases. ¹⁾

The candiru (Vandellia cirrhosa) lives in the rivers of the Amazon and feeds exclusively on the blood of larger fish, entering their gills and biting through their blood vessels. It satisfies its hunger within a minute and swims away in search of new prey, which it finds by the smell of ammonia emitted from its gills as it breathes. ²⁾

The Picasso Triggerfish (Rhinecanthus aculeatus) is a species of marine blowfish. It inhabits coral reefs and is kept in aquariums. The body of the fish has a multicolored arrangement of streaks and spots, reminiscent of Pablo Picasso's sketches - hence the usual species epithet. Picasso's Triggerfish has been used in studies of color vision in fish. ³⁾

The coastal dugong (Dugong dugon) is a marine mammal belonging to the order Coastals. The eyelids of Dugong glands are secreting oily fluid, which protects the eyes from the influence of strong salty seawater. After pulling the dugong above the water surface the secretion collects in the corner of the eye in a form of the so-called mermaid's tear, which is sometimes treated by the peoples of Oceania as an amulet. ⁴⁾

The American paddlefish, polychaete, paddlefish (Polyodon spathula) is a species of freshwater sturgeon fish in the paddlefish family. It is found in the Mississippi River basin and Lake Erie. It was imported to Poland in the 1990s. The snout - a rostrum shaped like a horizontally arranged paddle - is sometimes half the length of the whole body and is a sensory organ. ⁵⁾