Barred topminnow

Where they come from

Barred topminnows (Quintana atrizona) are one of those cool little surface fish from Mexico that most people never see in shops. They come from spring-fed waters and smaller streams, where the flow is usually gentle and there are plants or overhanging edges to hang under. They act like a tiny predator that lives in the top inch of the water.

Setting up their tank

Think long and low more than tall. These fish patrol the surface and like horizontal room, plus they get spooked if they feel exposed. A 20 gallon long works well for a small group, and bigger is even easier.

Give them cover at the top. Floating plants, overhanging stems, or even a strip of taller plants that reach the surface makes a huge difference in how bold they act. I have had the best luck with a calm top layer and gentle flow rather than a strong current blasting the surface.

• Tank size: 15-20 gallons for a group, longer footprint preferred
• Filtration: gentle, with the outflow aimed to avoid too much surface turbulence
• Decor: floating plants (salvinia, frogbit), guppy grass, hornwort, or tall stems reaching the surface
• Lighting: moderate, shaded spots help them feel secure
• Substrate: whatever you like - they do not care much since they live up top

For water, keep it stable and clean. Neutral to slightly alkaline tends to suit them, and they usually appreciate harder water. Temperature-wise, I treat them like a subtropical livebearer: comfortable in the low to mid 70s F, and they can handle a bit cooler if your room runs that way. Sudden swings and neglected water changes show up fast as skinny fish or constant hiding.

What to feed them

They are surface hunters. If you feed only sinking food, they will miss meals and you will wonder why they look pinched. Floating and slow-sinking foods are your friend.

• Daily staples: high-quality small floating pellets, crushed flake, micro granules that hang at the surface
• Best conditioning foods: live or frozen mosquito larvae, daphnia, cyclops, baby brine shrimp
• Occasional treats: chopped bloodworms (not as a main food), small insects if you culture them

How they behave and who they get along with

Barred topminnows are alert and a bit intense. Males can be pushy, and the whole group will do that surface stare-down thing where they track each other and anything that moves. In a planted tank with room, it is fun. In a bare tank, it can turn into constant stress.

Keep them in a group, but do not stack too many males together in a small footprint. A good starting ratio is one male to two or three females. That spreads attention and keeps females from getting ridden nonstop.

• Good tankmates: calm midwater fish that will not compete at the surface (small tetras, rasboras), peaceful bottom fish (corydoras, small plecos), livebearers that are not hyper-aggressive
• Use caution: other surface dwellers (hatchetfish, halfbeaks), nippy fish (some barbs), aggressive male guppies or endlers that never stop sparring
• Avoid: anything big enough to see them as food, or fish that harass the surface constantly

Breeding tips

They are livebearers, so you are not dealing with eggs. If the fish are comfortable and well fed, you may suddenly notice tiny fry hanging at the surface under floating plants. The adults are not model parents, so plan for cover.

• Give fry a fighting chance: dense floating plants and thick guppy grass are the simplest "nursery"
• If you want numbers: move a heavily pregnant female to a separate tank with floating cover and pull her back out after she drops
• Fry foods: baby brine shrimp is king; also use microworms, powdered fry food, and finely crushed flake
• Keep the surface calm: fry like still water and easy access to air-water line

Common problems to watch for

Most of the issues I have seen come from three things: not enough surface cover, not feeding the surface, and too much male pressure in too small a tank. Fix those and they are usually pretty steady fish.

• Jumping: nearly always a lid/coverage problem or a sudden fright event
• Skinny fish: food sinking too fast, bullying at feeding time, or internal parasites if appetite is strong but weight stays low
• Frayed fins: male sparring, cramped quarters, or nippy tankmates
• Clamped fins and hiding: too bright/bare at the surface, too much flow, or water quality slipping
• Mouth fungus/white spots: stress-related outbreaks after temperature swings or new fish introductions