American Flagfish tank mates
A working algae-crew killifish for temperate tanks. Eats hair algae, nips fins. Pair with corys and rasboras, never with shrimp or bettas.
Lists below are built from this species record (safest, best with, risky, unsafe) — each link opens a pair-level check, not a guarantee.
Best tank mates (on file)
Merged from conservative safest and best with fields — de-duplicated by species.
The American Flagfish profile lists Bristlenose Pleco as both safe and a recommended pairing. Bristlenose Pleco grows bigger than American Flagfish (15cm vs 6cm). Stock the American Flagfish group large enough to outnumber the Bristlenose Pleco, or the smaller fish ends up bullied or off food. Bristlenose Pleco swims in the bottom zone while American Flagfish stays in the middle, so the two will not crowd the same water column.
The American Flagfish profile lists Corydoras Catfish as both safe and a recommended pairing. Corydoras Catfish schools in groups of 6 or more, so plan room for the whole group rather than one fish. Corydoras Catfish swims in the bottom zone while American Flagfish stays in the middle, so the two will not crowd the same water column.
Risky or situational
From risky tank mates and broad avoid with (excluding “unsafe” below). May work with species-only setups, more water, or mature systems — read the pair page.
Marked risky or situational on the profile. Tank length and group size change the outcome more than a temperament label does.
Marked risky or situational on the profile. Tank length and group size change the outcome more than a temperament label does.
Fish to avoid with American Flagfish
From the unsafe list — predation, aggression, or space rules on this profile.
Betta conflicts with American Flagfish on temperament, predation, or footprint. The juvenile size in a shop tank is not the figure that matters here.
Angelfish reaches 20cm and is flagged predatory. American Flagfish at 6cm is prey-sized for it. Angelfish needs at least 150L, far above the 60L minimum for American Flagfish. The tank that houses one stresses the other.
Guppy conflicts with American Flagfish on temperament, predation, or footprint. The juvenile size in a shop tank is not the figure that matters here.
Cherry Shrimp conflicts with American Flagfish on temperament, predation, or footprint. The juvenile size in a shop tank is not the figure that matters here.
Neon Tetra conflicts with American Flagfish on temperament, predation, or footprint. The juvenile size in a shop tank is not the figure that matters here.
Tank size and groups
- Published minimum for American Flagfish: 60L — group minimum 1 .
- Compatibility changes when the tank is too short for turning, too little for a real school, or too warm for one species and not the other — that is why pair checks include tank context, not only temperament.
- Nearest litre hub to this minimum: 60L hub.
Easier alternatives to consider
Conservative beginner-peaceful picks from the library — not replacements for reading, but a shorter on-ramp than this species for a first tank.
Plan before you buy
Pair checks for every mix, then multi-species stocking in the builder.
Filtration & heating
A 60L minimum tank for American Flagfish needs a filter rated for at least 240L/hr turnover and a heater maintaining 18–28°C.
Similar fish (same category)
- Marbled Hatchetfish — min 60L
- Golden Wonder Killifish — min 80L
- Pea Puffer — min 40L
- Clown Killifish — min 20L
- African freshwater butterflyfish — min 150L
- Ropefish / reed fish — min 200L
- Senegal bichir — min 300L
- Black ghost knifefish — min 500L