Black Neon Tetra
Hyphessobrycon herbertaxelrodi
Black neons are one of those little tetras that look kinda understated until the light hits them-then that bright stripe pops and they shimmer when the school turns together. They're super chill, always cruising mid-water, and they make a tank feel "alive" without being hectic. If you keep a nice group, they get bolder and you'll see way more of their personality.
The Black Neon Tetra features a striking iridescent blue-green body and a prominent black stripe along its lateral line.
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Quick Facts
Size
1.3 inches
Temperament
Peaceful
Difficulty
Beginner
Min Tank Size
20 gallons
Lifespan
3-5 years
Origin
South America
Diet
Omnivore - small flakes/micro pellets, frozen foods like brine shrimp/daphnia, occasional live foods
Water Parameters
20-28°C
5-7.5
2-15 dGH
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Calculate heater sizeCare Notes
- Keep them in a real group (8-12+). A couple black neons look nervous and washed out, but a bigger school stays out and looks way better.
- A 20-gallon long (or similar footprint) is a commonly recommended size for a proper school; provide open mid-water swimming room with plants/wood/leaf litter and subdued lighting for security.
- They're pretty flexible, but they color up and act "normal" around 74-80°F, pH ~6.0-7.5, and moderate softness; sudden swings stress them way more than being slightly off the "perfect" number.
- Feed small foods they can grab mid-water: micro pellets, crushed flakes, plus frozen brine shrimp/daphnia a few times a week-just don't overdo it because they'll beg and then bloat.
- Great community fish with other calm small species (corys, small rasboras, dwarf gourami with a chill personality, most peaceful dwarf cichlids). Skip fin-nippers like serpae tetras and avoid big mouths (angelfish, larger barbs) that see them as snacks.
- If you see them chasing and nipping each other, it's usually a "too few fish / too bright / nowhere to hide" problem-bump the school size and add plants, and it settles down fast.
- Breeding is doable but fussy: they'll scatter eggs in fine-leaf plants or a spawning mop, and the adults will eat the eggs, so move the parents out right after spawning; keep the tank dim because the eggs/fry don't love bright light.
Compatibility
Good Tankmates
- Other small, chill schooling fish (ember tetras, rummynose tetras, cardinal/neon tetras) - they all vibe the same way, just keep everyone in proper groups so nobody gets stressed or nippy.
- Corydoras catfish - perfect bottom crew, totally peaceful, and they ignore the tetras while keeping the floor busy.
- Otocinclus - great little algae grazers that won't bother black neons; just make sure the tank is mature so the otos have food.
- Dwarf gourami / honey gourami (one of the calmer centerpiece options) - generally works well as long as the gourami isn't a jerk and the tank isn't cramped.
- Small, peaceful rasboras (harlequin/chili rasboras) - similar temperament and they share space nicely in a planted community setup.
- Apistogramma or other mild dwarf cichlids - usually fine with black neons in a planted tank, but give the cichlid caves/territory so it doesn't get spicy during breeding.
Avoid
- Anything aggressive or predatory (most medium/large cichlids, arowana-types, big barbs) - black neons are small and will get chased, stressed, or straight-up eaten.
- Fin-nippers and hyper fish (tiger barbs, some serpae tetras) - even if they're not trying to kill anything, the constant nipping/harassing will wreck the vibe.
- Slow fish with fancy fins (bettas, long-fin guppies) - black neons aren't usually bad, but mixed tanks can turn into 'who's nipping whose fins' drama depending on personalities.
1) Where they come from
Black neon tetras come from the Paraguay basin in South America—think slow-ish, tannin-stained streams with leaf litter and roots. They’re basically built for “soft and cozy” water, but the nice part is they’re pretty adaptable once they’re settled in.
If you’ve ever kept regular neons: black neons have a similar vibe, but I find them a bit hardier and less dramatic about everyday tank life.
2) Setting up their tank
Give them space to school and they look 10x better. A 20-gallon long is a sweet spot, but a standard 10 gallon can work if you keep the group modest and stay on top of water changes.
- Group size: aim for 8–12+ (they’re way calmer and bolder in a real group)
- Temp: 74–78°F (they’re not super picky, but steady is better than chasing a number)
- Flow: moderate; they like gentle movement but not a river-tank blast
- Lighting: medium to low looks great; bright lights can make them hide more
- Decor: plants + some open swimming room; dark substrate makes their stripe pop
If you want that “black neon glow,” add a little leaf litter or driftwood. You don’t need to turn the tank into tea, but a slight tint plus darker substrate makes their colors stand out.
They do best in a mature, stable tank. Fresh setups with new-filter wobble are where people run into losses and then blame the fish.
They’ll survive in a small group, but you’ll see more fin nipping and more hiding. Most “behavior problems” with these are just not enough buddies.
3) What to feed them
Black neons aren’t fussy eaters. In my tanks they take flakes immediately, but they really color up and fill out with a mix of dry and frozen/live foods.
- Staple: quality micro pellets or crushed flakes (small mouths)
- Frozen: daphnia, baby brine shrimp, cyclops, chopped bloodworms (treat, not every day)
- Live (if you do it): baby brine shrimp or microworms—great for conditioning and picky newcomers
- Feeding rhythm: small amounts 1–2x/day; they’re better with “little and often” than huge dumps
Watch the first 30 seconds of feeding. If a couple fish always hang back, try a finer food or feed in two spots so the shyer ones don’t get outcompeted.
4) Behavior and tankmates
They’re classic schooling tetras—busy, curious, and generally peaceful. You’ll see little chase games, but it’s usually just “tetra politics,” not real fighting.
- Great tankmates: other peaceful tetras, rasboras, corydoras, otocinclus, small plecos, peaceful dwarf cichlids (like rams), most shrimp in a planted tank
- Use caution with: long-finned fish (guppies, bettas) if your group is small or cramped
- Avoid: aggressive barbs, fin-nippy species, big enough predators to see them as snacks
They’re a nice “middle of the tank” fish. Pair them with bottom dwellers like cories and you get a really balanced, active community.
5) Breeding tips (if you want to try it)
Breeding black neons is doable, but it’s one of those projects where the setup matters more than luck. They’re egg scatterers, and yes—adults will absolutely eat the eggs if they get the chance.
- Breeding tank: 5–10 gallons, sponge filter, dim light, heater
- Egg protection: Java moss, spawning mop, or a mesh/egg crate bottom so eggs fall out of reach
- Water: softer and slightly acidic helps (if your tap is hard, mixing in RO can make life easier)
- Conditioning: feed frozen/live foods for a week or two
- Spawning: often happens early morning; remove parents right after you see eggs
- Fry food: infusoria or very fine powdered fry food at first, then baby brine shrimp
Keep the breeding tank pretty dark. Bright light seems to reduce hatch/survival, and fungus can be more of a problem when eggs are exposed.
6) Common problems to watch for
Most issues I’ve seen with black neons come down to stress from unstable water, being kept in too small a group, or being added to a brand-new tank.
- Faded color / clamped fins: usually stress—check temperature swings, ammonia/nitrite, and bullying
- Fin nipping: often a small school, cramped tank, or not enough plants/breaks in line-of-sight
- Ich after a new addition: common in community tanks—quarantine new fish if you can
- Skinny fish that still eat: internal parasites can happen; watch for stringy white poop and weight loss
- Sudden losses after purchase: shipping stress + uncycled tank + big parameter changes is the usual combo
They don’t like big, fast changes. If you’re adjusting pH/hardness, do it slowly—stability beats chasing “perfect” numbers every time.
My simple success recipe: a bigger school, lots of plants, steady temps, and smaller-but-regular water changes. Do that and black neons are about as beginner-friendly as it gets.
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