Red-tailed Black Shark

It is not a real shark; it is a cyprinid named for its silhouette and tall dorsal fin. With its velvety black body and bright red tail it is very striking. It looks docile when young, but as it matures it defends its territory fiercely.

In the wild it is considered extinct or close to extinction; all specimens in the hobby are farm-bred.

It is known to live in the rivers and streams of Thailand, over rocky, root-filled bottoms and in areas flooded during the rainy season.

• Volume: at least 200 liters and 120 cm in length; a large footprint is important.
• Decor: a bottom divided by roots, caves and rocks; a hiding place it can claim as its territory.
• Water: 24–26°C, clean and well oxygenated; it likes gentle flow.
• Lid: it jumps.

Omnivorous; it grazes algae and biofilm from surfaces. Sinking granules and tablets, spirulina, vegetables (zucchini, cucumber) and frozen foods.

It sets up a territory in the bottom and middle levels and chases fish that enter it. It is most aggressive toward its own kind and fish of similar shape and color (other "sharks", bottom fish with a similar mouth and body shape).

Good companions: fast schooling fish of the middle level (barbs, danios, large rasboras), angelfish and gouramis (in a large tank), bristlenose plecos (with enough hiding places).

Avoid: a second red-tailed black shark or similar "shark" species, corydoras and other peaceful bottom fish (they are chased constantly), very shy species.

The red-tailed black shark is kept on its own; two individuals in a small tank fight to the death. In very large (500 liters or more) tanks divided up with decor, a group of 5 or more can be attempted, but this is not recommended for hobbyists.

It almost never breeds in the aquarium; commercial production is done on farms with the help of hormones.

Hardy. In a stressed or sick fish the red tail fades to orange-pink; this is a warning to check the water parameters.

Hard to tell apart externally. Mature females have a fuller belly; males are slimmer with a more pointed dorsal fin.