Bleeding heart 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.

Typically wild-caught; acclimate slowly.

Feeding

An undemanding omnivore. Flake, pellets, frozen bloodworm, frozen brine shrimp, frozen daphnia, and live foods are all accepted. Feeding zone is the middle of the water column. The mouth is larger than on most community tetras, so standard pellet and flake sizes work without crushing. Two meals a day is enough. Colour stays brightest on a diet that includes regular live or frozen food in addition to a dry staple.

Compatibility

• A larger tetra (around 6 to 7 cm) that needs more swimming space than a beginner usually expects. A school of eight in a 150-litre tank is a reasonable starting point. In smaller tanks the school becomes tense and starts nipping
• Male-on-male sparring is part of normal behaviour, with lateral displays and fin-flaring rather than serious fights. Injury is uncommon unless a losing male has nowhere to escape
• Suits medium-sized peaceful community tankmates: other large tetras, barbs, rainbowfish, dwarf and medium cichlids, and corydoras-class bottom dwellers. Too big and active to be a good companion for very small fish (boraras, ember tetras) which tend to retreat in their presence
• The vivid red spot on the flank that gives the species its name is visible in both sexes and is the field-mark used to tell the species from rosy tetras. Mature males also develop the elongated sickle dorsal fin and slightly richer body colour

Origin and habitat

A larger characin from the upper Amazon basin in the 'Tres Fronteras' area, where the borders of Brazil, Peru, and Colombia meet. The species was described in 1943 by Henry Weed Fowler from the border region between Peru and Brazil, originally as Hemigrammus erythrostigma. It has since cycled through Hyphessobrycon (the name still used by most retailers and most older literature) and, since the September 2024 revision of characid taxonomy, sits in the genus Megalamphodus within the new subfamily Megalamphodinae (the 'red tetras') in the family Acestrorhamphidae. The species epithet means 'red brand' or 'red mark', describing the crimson spot on the flank that gives the fish its English name. Its range stretches from the rio Purus in Brazil upstream at least as far as the Nanay watershed near Iquitos in Peru, with additional populations in Colombian tributaries. Natural habitat is slow-moving water: tributary backwaters, side arms, and forest lakes, typically tannin-stained and shaded by overhanging vegetation, with submerged roots and branches providing cover. The species sits in the rosy tetra clade as proposed by Weitzman and Palmer in 1997, a group named for their pink-to-red body colour, elongated male finnage, and several anal-fin and dentition characters. Two sister species also carry the 'bleeding heart' label: M. pyrrhonotus and M. socolofi, both of which share the red shoulder spot. The body is deep and laterally compressed, greyish-green to brown on the back fading into a pinkish flank. Mature males develop one of the most exaggerated dorsal fins in the characin family: a tall, sickle-shaped sail that can stretch back to the caudal fin. Adult size in the trade is around 6 to 7 cm; published measurements give 29 to 61 mm for males and 29 to 53 mm for females (Animal Diversity Web). IUCN Least Concern. Most aquarium fish are wild-caught from Peru, though commercial breeding in Asia is increasing.

Breeding

An egg scatterer with no parental care, and one of the harder tetras to spawn at home. Commercial farms succeed with prepared soft-water systems, but in a typical hobby tank the species is famously reluctant. The basic approach is to condition a group on heavy frozen and live food for two to three weeks, then move the conditioned fish (often a group of three males and three females, since pair spawning tends to fail more often) into a separate, dimly lit tank with very soft and acidic water (pH around 5.5 to 6.5), fine-leaved plants or spawning mops, and a darker base. Spawning is usually triggered by the first light of morning and happens during a side-by-side display. Eggs are semi-adhesive and scatter through the plants; the parents eat them given the chance and need to come out as soon as spawning is finished. Hatching takes roughly one to three days depending on temperature, and the fry are free-swimming a few days after that. First foods are infusoria or a fine commercial liquid fry food, then baby brine shrimp once the fry are large enough.

Common problems

Male sparring is the most visible behaviour and looks more dramatic than it actually is. Adults flare their extended dorsal fins and circle each other, and minor tears can result, but persistent injuries usually mean the tank is too small for the loser to retreat from the winner. The flip side of the same behaviour is that in groups under about six, the fish become tense and start nipping other species; eight or more largely absorbs the aggression inside the school and leaves tankmates alone. Wild-caught stock often arrives carrying internal parasites that cause slow wasting even in fish that appear to be eating, so quarantining new arrivals and treating with an antiparasitic such as praziquantel is sensible. The species is more sensitive to nitrate than many community tetras; keeping nitrate well under 40 ppm with regular water changes improves longevity and colour. Columnaris and other bacterial infections appear when water quality slips. Typical lifespan is around four to five years in good conditions.

Bioload

Further reading

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