Serpae tetra

Water parameters

Tolerated range for this species. Aim for the middle of each band rather than the extremes.

Tank and habitat

Substrate: any.

Behavior

Plant interaction: plant safe.

Feeding

Omnivore, eats everything. Flake, pellets, frozen bloodworm, frozen brine shrimp, frozen daphnia, live food. Feeds in the midwater column. Aggressive feeders that outcompete slower species. Feed twice daily. A varied diet with frozen food maintains the deep red body color.

Compatibility

• Fin-nipper. Not as aggressive as tiger barbs, but persistent enough to shred long-finned fish over time. Bettas, angelfish, and fancy guppies are not safe tankmates.
• Keep in groups of 8+ to contain the aggression within the school. In small groups (under 6), serpae tetras redirect their nipping outward and become a menace to everything else in the tank.
• Best with other robust, fast fish that can handle the occasional chase: larger tetras, barbs, rainbowfish, and catfish. Other semi-aggressive species that can hold their own.
• The deep red body coloring makes them one of the most visually striking tetras available, which is why they keep getting recommended despite the behavioral baggage.

Origin and habitat

Widely distributed throughout much of the Amazon drainage in Brazil, Peru, and Bolivia, plus the Río Paraguay system in Brazil, Paraguay, and northern Argentina; the upper Paraguay is connected to the Amazon via the Río Guaporé. H. eques is recognized as a species complex, and H. serpae is a junior synonym. Found in slow-moving or still backwater habitats including ponds, small lakes, streams, and flooded forest areas, typically near dense vegetation, leaf litter, and submerged branches. Also known as jewel tetra, red minor tetra, blood tetra, and callistus tetra (USGS, multiple sources). Body is deep red to reddish-brown with a characteristic black comma-shaped mark behind the gill cover; the dorsal fin shows bold black coloration. Grows to about 4–5 cm. A long-finned captive-bred variety exists. Known for fin-nipping, particularly problematic with long-finned tankmates; keeping them in larger groups of 10+ with visual barriers can reduce but not eliminate this behavior. Commercially bred in large numbers for the trade.

Breeding

Egg scatterer, standard tetra breeding protocol. Condition pairs with frozen food. Breeding tank with soft, acidic water (pH 6.0-6.5), dim lighting, and fine-leaved plants. Temperature at 26–27°C. Spawning occurs at dawn. The pair scatters 200-300 eggs among plants. Eggs are light-sensitive. Remove adults after spawning. Eggs hatch in 24-36 hours. Fry need infusoria for the first few days, then baby brine shrimp. Growth is moderate. The species breeds readily in home setups; the difficulty is average for an egg-scattering tetra.

Common problems

Fin nipping is the defining issue and the reason experienced keepers either love or avoid them. In the right setup (large group, robust tankmates, plenty of space), serpae tetras are stunning and mostly well-behaved. In the wrong setup (small group, slow tankmates, cramped tank), they're destructive. Health-wise, they're tough. Ich in new purchases is the standard risk. Columnaris can occur in degraded water. The species is otherwise hardy and long-lived (5-7 years). A common frustration: the red coloring that looked so vivid in the store fades at home because the store used colored background lighting. In a home tank with natural lighting, serpaes still look good but not quite as dramatically red.

Bioload

Further reading

• How to cycle a fish tank
• Stocking ideas by tank size