Serpae Tetra (Megalamphodus eques)

Serpae Tetra (Megalamphodus eques) is a bold red South American tetra known in the UK aquarium trade as the Serpae Tetra, Red Minor Tetra, Jewel Tetra and Flame Tetra. Older books and supplier records may use Hyphessobrycon eques or Hyphessobrycon callistus; current FishBase treatment places those names in synonymy under Megalamphodus eques. Keeping those older names once in context preserves useful search recognition without turning the page into a list of repeated keywords.

Serpae Tetras are active shoaling fish rather than quiet background tetras. Their colour and movement can make an excellent planted-community display, but they can nip fins when kept in too small a group, in a cramped aquarium or with slow long-finned tank mates. Plan the aquarium around a proper shoal and adult behaviour, not the small dispatch size.

Quick care

Aquarium size and layout

Use a mature aquarium with useful horizontal swimming room. Around 60 litres can work for a small group, but a larger aquarium makes it much easier to keep eight to twelve fish and add compatible tank mates without concentrating social pressure. In a mixed community, 75–90 litres or more is a more comfortable starting point.

Plant the sides and rear while leaving open midwater space. Dark sand or fine gravel, wood, shaded planting and floating cover can help the red body colour look stronger and give lower-ranking fish somewhere to move out of sight. Avoid creating one bright, bare box where the shoal has nowhere to break contact.

Use a secure lid and smooth décor. Serpae Tetras can move quickly when startled, so leave clear swimming lanes and avoid sharp objects or narrow traps.

Water parameters and filtration

Keep the aquarium around 22–27°C with a practical pH of 6.0–8.0. Captive stock is adaptable, but sudden temperature, pH or hardness changes are still stressful. In a UK home, test the source water before making adjustments rather than assuming every tap supply is the same.

Ammonia and nitrite must remain at zero. Keep nitrate controlled with mature biological filtration, measured feeding and regular partial water changes. Gentle-to-moderate flow and good surface movement are suitable; this species does not need a high-current river setup.

Do not chase a perfect pH by repeatedly adding chemicals. Stable replacement water and a predictable maintenance routine are more useful than pushing the tank from one end of the range to the other.

Group size and fin-nipping behaviour

Serpae Tetras are often described as semi-aggressive, but the most useful description is active shoaling fish with a real potential to nip fins. Group structure matters. We recommend at least eight, with ten to twelve preferable where the aquarium can support them. A larger shoal spreads display and chasing between more fish.

Brief chases and fin displays within the group can be normal. Persistent attacks, one fish being isolated, repeated fin damage or tank mates hiding at feeding time are not. Increase visual cover, review group size and reconsider incompatible tank mates rather than assuming nipping is unavoidable.

A six-fish minimum is often quoted, but treating six as a target rather than a bare minimum can leave the group less settled. If space allows, a larger shoal generally gives a better display and more natural social behaviour.

Feeding

Use a quality fine flake, micro-pellet or small slow-sinking granule as the staple. Rotate appropriate frozen or live foods such as daphnia, cyclops and Artemia, with bloodworm used in sensible portions. A varied diet supports colour and body condition without requiring heavy feeding.

Feed small portions once or twice daily and distribute food across more than one part of the surface. Serpaes are quick feeders, so watch that quieter fish in the group receive food. If food reaches the substrate uneaten, reduce the next portion.

Overfeeding will not make the fish less nippy if the real problem is crowding or group structure. It simply adds waste and increases the load on the filter.

Tank mates

Choose robust, active community fish that share similar water conditions. Other medium-small tetras, suitable rasboras and peaceful bottom dwellers such as Corydoras can work in a sufficiently spacious planted aquarium. The exact combination depends on adult size, swimming speed and available space.

Avoid male Bettas, guppies with large flowing tails, long-finned Angelfish and other slow ornamental fish likely to attract nipping. Tiny fish can also be intimidated by a fast Serpae shoal. Adult shrimp may survive in heavily planted aquariums, but shrimplets are likely to be eaten.

Neon or Cardinal Tetras can sometimes coexist in a larger, well-planted aquarium, but Serpaes are more assertive. If the aim is a very calm tetra community, a gentler species may be a better choice.

Plants and aquascaping

Serpae Tetras work well in planted aquariums and do not normally destroy healthy plants. Java fern, Anubias, Cryptocoryne and stem plants can provide useful structure. Floating plants help soften bright lighting while retaining an open midwater lane.

Moderate lighting is sufficient. Very bright bare setups can make fish nervous and washed out. A regular day/night cycle with a dark rest period supports normal behaviour.

Sexing and breeding

Mature males are generally slimmer and can be more intensely coloured, while females become fuller through the body when carrying eggs. Young retail fish are difficult to sex confidently, so this listing does not guarantee sex unless a future option explicitly says so.

Serpae Tetras are egg scatterers. Breeding is normally attempted in a separate aquarium with soft, slightly acidic water, dim lighting and fine-leaved plants or spawning mops. Adults can eat eggs, so they are usually removed after spawning.

Fry need very small first foods before progressing to newly hatched Artemia and fine prepared fry diets. Stable clean water is especially important because feeding tiny foods can foul a small breeding aquarium quickly.

Health and warning signs

A healthy shoal should be active, balanced, feeding readily and holding open fins. Faded colour immediately after transport can be normal. Persistent clamped fins, white spots, rapid breathing, weight loss, skin damage or one fish repeatedly leaving the group should trigger water testing and a health check.

Fin damage is not always a disease. If several fish have torn fins, review nipping and compatibility before automatically adding medication. Quarantine new fish where a suitable mature system is available and treat only when there is a reason to do so.

Acclimation and the first week

Prepare the aquarium before delivery. Confirm temperature and water quality, keep the lights subdued during introduction and follow the current receiving instructions supplied with the order. Avoid heavy feeding on arrival day.

During the first week, observe shoaling, breathing, appetite and fin condition. If the fish hide or chase constantly, review the layout and tank mates as well as water chemistry. Do not add another new group immediately while the Serpaes are still settling.

Serpae Tetra compared with gentler red tetras

Mobile buying summary

• What you receive: one unsexed Serpae Tetra in the selected live size.
• Adult size: around 4–5 cm.
• Group: at least eight; 10–12 is preferable.
• Best home: mature planted community aquarium with open swimming space.
• Key behaviour: active and potentially fin-nipping.
• Avoid: slow long-finned tank mates and cramped groups.
• Current stock, size and price: use the live product selector.

Before ordering

Choose Serpae Tetras if you want a lively red shoal and can provide enough space for a proper group. Reconsider if the aquarium is tiny, newly cycled, or built around long-finned peaceful fish.

The earlier version repeated dozens of search questions and unrelated shopping phrases. This version keeps the useful search topics—Serpae Tetra size, tank size, group size, water, feeding, tank mates, fin-nipping, breeding and sexing—but answers them in natural UK aquarium language that is easier to scan on a phone and clearer for Google, Shop and AI systems.