Red Phantom Tetra
Hyphessobrycon sweglesi
Min Tank Size
75L
Adult Size
3.5 cm
Lifespan
5 years
School Size
6+
About
Native to the Orinoco basin in Venezuela and Colombia, the Red Phantom Tetra is one of those fish that looks almost unreal under the right lighting. Their bodies carry a deep, translucent ruby-red hue with a prominent dark humeral spot just behind the gill plate, and the dorsal fin often sports a striking black marking edged in white. Compared to their close cousin the Rosy Tetra, they tend to run a deeper, richer red, which makes them real standouts in a planted blackwater setup. They stay small, topping out around 3.5 cm, and are completely peaceful with anything they can't swallow.
Water chemistry matters more here than with some hardier tetras. These fish genuinely do better in soft, slightly acidic water. A pH between 5.5 and 7.0 with low general hardness keeps them healthy and looking their absolute best. Tannin-stained water from Indian almond leaves or driftwood not only mimics their natural environment but also seems to reduce stress and deepen coloration noticeably. They're not bulletproof in hard, alkaline tap water the way neon tetras can sometimes get away with being.
Feeding is straightforward. They'll take quality micro pellets, crushed flakes, and relish frozen foods like daphnia, baby brine shrimp, and bloodworm. Varied diet keeps their color vivid.
A school of at least six is really a minimum for welfare, and a group of ten or more swimming together through a densely planted aquascape is genuinely one of the more beautiful sights in the hobby. Browse community tank builds featuring this species and you'll find them again and again in South American biotopes and lush Amazonian-style setups for good reason.
Water Parameters
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Flow Preference
Keeping multiple Red Phantom Tetra together
Red Phantom 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 play well with almost everything in the nano-to-community size range. Corydoras, dwarf cichlids like apistogramma, small loaches, pencilfish, other small tetras, and hatchetfish all work well. Avoid anything boisterous or nippy like tiger barbs or large semi-aggressive cichlids. Dwarf shrimp such as neocaridina and caridina can coexist, but juveniles and recently molted adults are at some risk in a tank without dense cover. They're a natural fit for South American biotope setups alongside German blue rams or chocolate gouramis. Aim for a tank with plenty of plant cover to make everyone comfortable.
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 them in hard, alkaline tap water and wondering why they look washed out or keep getting sick. Water chemistry is genuinely the make-or-break factor with this species. Soft, acidic water isn't optional for long-term success. Tannins help. Another issue is understocking the school. Four fish will look stressed and pale. Eight or more and they school tightly, show full color, and behave naturally. They're also more delicate during transport and acclimation than hardier tetras, so a slow drip acclimation is worth doing.
Behavior & Aggression
Red Phantom Tetras are about as peaceful as tetras get. There's virtually no fin nipping, no territory disputes, and no meaningful aggression toward tankmates. The only caveat is within a very small or cramped group, where occasional mild chasing can occur during spawning behavior or competitive feeding. Keeping a proper school of six or more distributes any social tension naturally and keeps everyone calm. They're not a threat to anything that isn't bite-sized.
Things to Know
- Needs soft, acidic water to show best color and thrive long-term.
- May pick at dwarf shrimp, especially juveniles and newly molted adults.
- Subdued lighting and dark substrate bring out the deepest red coloration.
- Males will spar harmlessly, displaying for females.
- Can be shy and lose color in bright, open tanks.
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