Order Siluriformes
Family Callichthyidae
Subfamily Corydoradinae
Genus Dianema
This genus is very close to the genus Callichthys. It is distinguished from the latter by its deeply incised caudal fin. Two pairs of long barbels are extended forward. The female can be distinguished from the male by the size of her belly (it is fuller in the female). Peaceful fishes, often keeping in groups in the lower and middle water layers. When the aquarist makes sudden movements, they dart about in fright and may bury their heads in the substrate. They need hiding places and plants.
— Porthole Catfish — Dianema longibarbis [Cope, 1872]. Synonyms: Callichthys adspersus, Decapogon verissimi. Amazon River basin in Peru and Brazil. They inhabit the shores of slow-flowing water bodies, pristine forest streams, and lakes with muddy bottoms. Reaches a length of 8-9 cm.
The body is rounded, elongated, covered with large scales arranged in two rows like shingles. Between the adipose and dorsal fins, there are four bony plate-like outgrowths. Such outgrowths are also present in the middle of the body. The snout is conical. The barbels are long, about 3-3.5 cm, one pair is positioned horizontally, the other points downwards. The caudal fin is slightly forked.
Depending on maintenance conditions, the coloration is variable, ranging from light brown to bronze with slightly shaded fins. The whole body is covered with a large number of small black spots, which merge in the middle of the body into a dark interrupted stripe. Each scale of the upper row has 3-4 small black spots. The scales of the lower row are lighter, and the spots on them are smaller. Dark brown spots run across the body, forming a pattern of interrupted stripes (one longitudinal and many transverse ones).
The fins are transparent, well-developed, yellow in the light. The belly is light, darkens when excited, acquiring a brownish-orange color. Males have somewhat more elongated rays of the pectoral fins and are slimmer than females. In adult males, the belly line is almost straight. Similar to Callichthys, but has a deeply forked caudal fin.
Peaceful, willingly stays in the water current. Unlike a number of other catfishes, representatives of this genus sometimes freeze in place in the middle water layers and then calmly continue their movement. A schooling fish, easy to keep, and does well in the company of other small peaceful fish species; they do not bother even the fry of livebearing toothcarps. Can be kept in a community aquarium with a small number of plants, hiding places made of driftwood, and ample swimming space up to the upper layer. Prefers dim light and plenty of hiding places in shaded areas of the bottom.
Peated water, soft to moderately hard. Filtration, aeration, weekly water changes. In search of food, they actively muddy the aquarium substrate. When maintaining the aquarium, the fishes begin to dart around and often bury their heads in the substrate, so the substrate should be soft. Like all members of the Callichthyidae family, Dianema periodically rise to the water surface and swallow atmospheric air.
They readily eat both live and dry types of food, but prefer bloodworms, which they easily extract from the silt. They reach maturity at 12-15 months. Males build a small bubble nest on the underside of broad-leaved floating plants. The male cares for the eggs and keeps other fish away from the nest. pH 6.5-7.5; dH 4-10°; T 22-26°C.
Identification: Dianema longibarbis.
— Flag Tailed Hoplo, Flag Tailed Porthole Catfish — Dianema urostriatum [Miranda & Ribeiro, 1912]. Rio Negro, Amazon rivers, Brazil, Peru. 12 cm. The torpedo-shaped body ends in a massive caudal fin lobe. At the corners of the mouth, there are two pairs of long barbels (reaching almost a third of the body length). A distinctive feature is randomly placed dark spots on the sides and back, forming a certain pattern. The main tone is bright beige-brown with dark speckles, a white throat and belly. Small dark spots are scattered across it. The lower part of the body is silvery-gray.
The caudal fin is white, forked, with 5 horizontal black stripes; the central one extends to the base of the tail, and two white and black horizontal stripes run along the upper and lower lobes from the central stripe. All other fins are colored to match the body tone. It is easily distinguished from Dianema longibarbis by its black and white striped caudal fin. The male is brighter and slimmer. Males have a thick red-brown first ray of the pectoral fins.
Peaceful, willingly stays in the water current. A schooling fish, easy to keep, and does well in the company of other peaceful fishes. The fishes constantly move in search of food, probing various corners of the aquarium with their barbels, muddying the substrate. In the evening and at night, the fishes become more active; at night they feed and stay awake. When frightened, the fishes can bury themselves in the sand and hide in shelters.
Can be kept in a community aquarium with dense plants, hiding places, and ample swimming space up to the upper layer. Does not damage plants, but due to the habit of constantly digging in the substrate for food, it is undesirable to use plants with finely divided leaves. Substrate should be sandy. Filtration, aeration, weekly water changes. Animal and combined food is recommended. They reach maturity in 1.5 years. The male builds a nest of air bubbles and tends to the eggs. dH up to 20°; pH 6.5-7.5; T 20-28°C.
Identification: Dianema urostriatum.
Lepthoplosternum pectorale, Megalechis thoracata. 
