Redeye Tetra

Redeye Tetra (Moenkhausia sanctaefilomenae) 

Care & Breeding Notes

A striking and active schooling fish, the Redeye Tetra thrives when kept in groups of six or more. I currently have a group of six as the tank has only recently completed its cycle. Over the next week I’ll continue monitoring water parameters and performing any necessary water changes before increasing the shoal.

Natural Habitat

Redeye Tetras are surface‑oriented swimmers native to flowing, plant‑rich rivers across Brazil, Bolivia, Venezuela, Paraguay, and Uruguay. Their range includes the Parnaíba, São Francisco, upper Paraná, Paraguay, and Uruguay river basins.

Size & Lifespan

• Adult size: ~7 cm (2 ¾")
• Lifespan: 3–5 years in captivity

Temperament

They are generally peaceful community fish, though they may occasionally nip the fins of slow‑moving or long‑finned tankmates. It’s worth keeping an eye on more delicate species.

Aquarium Setup

Water Parameters

• Temperature: 24–28°C
• pH: 6.0–8.0
• KH: 5–20°
• My current setup: 24.5°C, pH 6.8, KH 5

Redeye Tetras adapt well to a wide range of conditions. Planted and floating plants, botanicals and driftwood make excellent décor and help replicate their natural environment.

Diet

These fish are omnivores and benefit from a varied diet. Mine receive a rotation of:

• Micro granules
• Flake food
• Daphnia
• Baby Brine Shrimp
• Bloodworms

Breeding Project

As part of my ongoing project with this species, I’ll be attempting to breed them.

Sexing

Males tend to be slimmer, while females develop a slightly rounder, fuller body—especially noticeable once they mature. This may take some time after purchase.

Breeding Tank Setup

Redeye Tetras are egg scatterers, so a dedicated breeding tank is essential to prevent the eggs from being eaten.

Recommended setup:

• Soft, tannin‑rich water (achieved with leaves, botanicals, or peat filtered through floss)
• A cycled sponge filter
• A plastic grid or mesh to protect eggs from the adults
• 1–2 females with 1 male

Spawning Method

1. Introduce the fish to the breeding tank and leave them undisturbed.
2. After 24–48 hours, perform a 50% water change using freshly collected rainwater.
3. The following day, perform a 75% rainwater change.
4. Repeat this cycle as needed.
5. If spawning doesn’t occur, remove the male, feed the females well for a few days, then reintroduce him and restart the water‑change routine.

This method is commonly used for other tetra species, so with luck, it should also prove successful for Redeye Tetras.

If you'd like, I can also format this into a care sheet, a YouTube script, or a branded AquaExotics‑style guide.