Glass Bloodfin Tetra
Prionobrama filigera
Min Tank Size
75L
Adult Size
6 cm
Lifespan
7 years
School Size
6+
About
Native to the river drainages of Bolivia, Brazil, and Argentina, Prionobrama filigera occupies a pretty unique visual niche in the hobby. The body is almost completely see-through, glassy enough that you can make out the spine and internal organs under good light, and the tail blazes red in contrast. It's a striking combination that photographs beautifully, especially against dark substrate or tannin-stained water.
Despite looking delicate, these fish are genuinely tough for a tetra. They tolerate a wider temperature range than most, handle moderate hardness without complaint, and don't require pristine blackwater conditions to thrive. Soft, slightly acidic water will bring out their best color, but they're adaptable enough that a beginner with decent tap water shouldn't struggle.
They're mid-to-top swimmers that zip around with purpose, rarely sitting still. A school of eight or more in a planted tank is genuinely stunning to watch.
Diet is uncomplicated: quality flake or micro pellets form the base, with occasional live or frozen foods like daphnia or baby brine shrimp to keep them in peak condition. They don't demand much, but they do reward the extra effort.
Peaceful across the board, they mind their own business and never cause problems in a well-chosen community. If you want to see what a working planted community tank actually looks like with glass bloodfins in it, browsing build logs and tank journals from other hobbyists is absolutely worth your time.
Water Parameters
Temperature
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GH
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Flow Preference
Keeping multiple Glass Bloodfin Tetra together
Glass Bloodfin Tetra are shoaling fish and need company of their own kind. Keep a group of at least 6. Smaller groups leave them stressed, washed-out in color, and prone to hiding.
Compatibility
These tetras mix well with most peaceful community fish of similar size. Good pairings include other small tetras like rummy nose or ember tetras, pencilfish, small rasboras, corydoras, and smaller dwarf cichlids like apistogrammas that won't view them as food. Avoid housing them with anything large enough to swallow them or known fin nippers like tiger barbs, which will harass them even though glass bloodfins aren't particularly fin-vulnerable themselves. Adult dwarf shrimp like cherry or amano shrimp are generally fine, but shrimplets may occasionally be eaten. They're a natural fit for blackwater and South American biotope builds.
Commonly kept with
Species this one is most often paired withCommonly tried but avoid
Often paired, but shouldn't beCare Notes
The most common mistake is keeping too few, usually three or four, and then wondering why they're pale and hiding. Six is the real minimum, eight or more is where they genuinely thrive. They're also strong jumpers, and a surprising number of hobbyists lose fish to this before they realize the gap in their lid. Water quality doesn't need to be perfect, but consistent parameters matter more than chasing ideal numbers. They tend to fade in color under harsh lighting without any plant cover or structure to retreat to.
Behavior & Aggression
Glass bloodfins are genuinely peaceful and show no meaningful aggression toward other species or their own kind. In undersized schools, individual fish may become timid or erratic rather than aggressive, which stresses the whole group. Keeping six or more resolves this immediately. They don't nip fins, don't chase tankmates, and won't establish territories. Any chasing you observe is almost always spawning behavior between males during breeding activity, not aggression worth worrying about.
Things to Know
- Strong jumper, a tight-fitting lid is essential.
- May pick at very small shrimp or shrimplets, not adults.
- Needs a school of 6+ or stress-related issues appear quickly.
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