Tetras
Characins from South America, and almost all of them shoal. Kept in numbers they colour up and hold together; kept in twos they hide.
Photo by Mattia Nocciola, CC BY-SA 4.0
Overview
Tetra covers roughly 1,300 species of characins from Central and South America and Africa, and most of the ones cultured for the trade stay under 4 inches. They are egg scattering group spawners with no parental care, which is why they are farmed in enormous numbers and cost very little.
What they have in common as pets is the shoal. A tetra is a fish that only works in a group, and the single most common mistake with them is buying three or four of several kinds instead of eight of one.
Temperament
Active, peaceful and highly social. In a proper group tetras hold the middle of the water column, colour up properly and spend the day in the open. In a group too small they hide and fade.
A few species are nippy, serpae and black skirt tetras among them, and long finned tank mates like angelfish and bettas are what they nip. Choosing by species rather than by the word tetra avoids most of the trouble, since the family spans peaceful shoals and genuinely boisterous fish.
Care and grooming
Insects and crustaceans in the wild, so flake and micro pellets with frozen brine shrimp or daphnia as a supplement. Mouths are small, so the food has to be small.
Water is by species. Blackwater fish like neons and cardinals want it soft and slightly acidic, while many South American tetras are comfortable in ordinary moderately hard tap water. Across the group, 72 to 80 F and pH 6.0 to 7.5 covers most of what is sold.
Living and exercise
Twenty gallons, planted, with open water through the centre and cover at the sides. A dark substrate and dimmer light bring out colour that a bright bare tank washes out.
They occupy the middle, which makes them the natural partner for corydoras on the floor and something quiet at the surface. Buy one species in a group of eight or more rather than a mixed handful, because a shoal of one kind behaves like a shoal and an assortment does not.
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