Serpae tetras are energetic, colorful community fish best kept in a large shoal in a planted aquarium with open swimming space. They’re hardy and adaptable, but they are well-known fin-nippers—especially when kept in small groups or with slow, long-finned tankmates. A bigger group, a longer tank, and plants that break up sight lines usually reduce chasing and nipping. With the right tank mates, they become an active mid-water school that adds constant movement and red/orange color.
Quick Specs
Water parameters
| Temperature: | 72–79°F (22–26°C). Keep it stable; they’re adaptable but do best in consistent tropical conditions. |
| pH: | 6.0–7.5 (slightly acidic to neutral; stability matters most). |
| Hardness: | 2–15 dGH (soft to moderately hard). |
| Other: | Ammonia and nitrites must be 0 ppm at all times. Keep nitrates low (ideally under ~20–30 ppm) through regular water changes, controlled feeding, and adequate filtration. Stress from small group size, cramped tanks, or incompatible tankmates often increases chasing and fin-nipping. |
| Water changes: | Change about 20–30% weekly to maintain water quality. In smaller tanks or heavier stocking, 15–20% twice weekly can help keep nitrates down and reduce stress-related behavior. |
Behavior & compatibility
Schooling Behavior: Serpae tetras are shoaling fish and should be kept in groups. In a proper shoal they are more stable in behavior; in small groups they often direct aggression and fin-nipping toward tankmates.Temperament: Serpae tetras are known fin-nippers, especially when kept in small groups, cramped tanks, or with long-finned/slow tankmates. In a larger group with enough space and cover, fin-nipping can be reduced but not always eliminated.
Centrepiece: They are not a single centerpiece fish, but a large shoal can be a strong visual feature due to their red coloration and constant activity.
Prolific or Livebearing:They are egg layers (not livebearers). They may spawn in mature tanks, but they are not typically prolific in community setups because eggs/fry are usually eaten unless separated.
Swimming zone:They are mid-water fish that spend most of their time in the middle of the aquarium, rising toward the surface during feeding.
Interaction with Plants:Plant-safe and benefits from planted tanks. Plants break up sight lines and reduce chasing. Keep open swimming space in the middle with cover along the edges.
Setup essentials
Lid: A tank cover is preferred. They can jump when startled, and a cover also reduces evaporation and keeps conditions stable.Filter: A filter is necessary. Use gentle-to-moderate filtration with good biological capacity to keep water clean without excessive current. Stable water quality and good space planning help reduce stress and nipping.
Substrate: Dark sand or fine gravel is preferred, especially in planted tanks. Dark substrate and plants improve comfort and coloration and can reduce stress.
Lighting: Special lighting isn’t required, but moderate aquarium lighting is preferred for viewing and plant growth. Plants and shaded areas help reduce stress and chasing.
Heater: A heater is preferred and often necessary to maintain a stable tropical range (22–26°C), especially in cooler rooms or during seasonal swings.
Air Pump: An air pump is not strictly necessary if the filter provides good surface agitation, but gentle aeration is preferred in warmer tanks, higher stocking, or if oxygen seems low.
Feeding Regimen
Feed 1–2 times per day in small portions. They accept quality flakes and pellets and do well with frozen/live foods like brine shrimp, daphnia, and bloodworms a few times per week. Avoid overfeeding to protect water quality.Lifespan
With proper care, serpae tetras typically live about 3–7 years.Tank Mates
Good tank mates
robust, fast-moving community fish (rummy-nose tetras, black skirt tetras, harlequin rasboras in larger tanks), corydoras, bristlenose pleco, many danios (space dependent).
Avoid
long-finned/slow fish (bettas, fancy guppies, angelfish in many setups), timid nano fish that will be bullied, and small shrimp/shrimplets.
Note
if nipping persists, increase shoal size, add more plants/wood to break lines of sight, and remove the most targeted long-finned fish.
Common problems + quick fixes
Increase shoal size (8–12+), provide more space and plants, avoid slow/long-finned tankmates, and ensure regular feeding.
Add line-of-sight breaks (plants/wood), provide open swimming space, and avoid overcrowding.
Reduce feeding, improve filtration, and do consistent 20–30% weekly water changes (or smaller changes twice weekly).
Quarantine new fish, stabilize temperature/parameters, and keep ammonia/nitrite at 0.
Interesting Facts
Serpae tetras are sometimes sold as “red minor tetras,” and their bright body color contrasts strongly with their dark fin edges. Their behavior changes dramatically with group size—small groups often behave much worse than larger shoals. In a well-structured tank, you can often observe social hierarchy behavior without serious damage.