Scarlet Badis

At no more than 2 cm, the scarlet badis is one of the smallest perch-like fish in the world. Males are eye-catching with bright red-orange bodies, up to seven bluish-white vertical bars and white-tipped pelvic fins; females are gray-beige and unremarkable.

It is one of the most beautiful choices for densely planted nano aquariums. However, it hardly ever takes dry food; it should not be bought unless you can regularly provide small live or frozen food.

It lives among dense aquatic plants in clear, shallow streams that flow into the Brahmaputra in northeastern India. Because of the region's subtropical climate, it also tolerates cool water.

• Volume: at least 40 liters for 1 male and 2–3 females; more floor space for more than one male.
• Decor: very dense plants, moss and fine-leaved plants; visual barriers reduce fighting between males.
• Water: 22–25°C is ideal; it also adapts to hard water. Gentle flow.
• Choice of companions: a species-only tank or very calm, small species.

Carnivorous. Live or frozen cyclops, daphnia, brine shrimp (newly hatched brine shrimp is best), grindal worms and small bloodworms. Feed small amounts 1–2 times a day. It feeds slowly and goes hungry alongside fast fish.

Males are territorial toward each other; they display by spreading their fins and coloring up, and serious injuries are rare. It is completely harmless to other species.

Good companions: dwarf shrimp (adult Neocaridina, Caridina), very small and calm fish such as Boraras, otocinclus, snails.

Avoid: fast-eating and large species, dominant fish such as dwarf gouramis, any species that might see it as food.

A harem setup: 1 male, 2–3 females. In a larger aquarium several males can live together, each claiming its own clump of plants.

The male lures the female among the plants; the eggs are laid one by one among moss and fine leaves. The parents provide no care and may eat the eggs and fry. In an aquarium with dense moss some fry grow up on their own; the fry are fed infusoria and then newly hatched brine shrimp.

• Starvation: the most common cause of death in fish not given suitable food.
• Internal parasites: in wild-caught fish; quarantine is recommended.

Easy: males are red and barred; females are gray-beige, smaller and colorless. Because males are sold more often in the trade, females can be hard to find.