Goulding's lampeye
Fluviphylax gouldingi
About the Goulding's lampeye
This is one of those truly tiny Rio Negro blackwater lampeyes - like, adult size is basically the length of a grain of rice. In the right light you can catch a little orange blotch on the face, and males have a neat filament on the pelvic fin. They do best in a calm, heavily planted (or leaf-litter) setup where micro-food is always available.
Also known as
Quick Facts
Size
1.4 cm SL
Temperament
Peaceful
Difficulty
Advanced
Min Tank Size
5 gallons
Lifespan
1-2 years
Origin
South America
Diet
Micro-predator - baby brine shrimp, microworms, daphnia/moina, cyclops, fine frozen foods; some may take tiny powder foods
Water Parameters
24-28°C
4-6.5
0-5 dGH
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Calculate heater sizeCare Notes
- Keep them in a mature nano tank (10-20 gallons is comfy for a group) with gentle filtration and lots of fine plants like moss, subwassertang, and floating cover - they hate being out in the open.
- They do best in soft, slightly acidic water: shoot for pH about 5.5-6.8, low KH, and temps around 75-80F; stability matters more than chasing a magic number.
- They are tiny micropredators, so skip big flakes - feed baby brine shrimp, microworms, small daphnia, and fine frozen cyclops; they do way better with small meals 1-2 times a day than one big dump.
- Avoid boisterous tankmates and anything that competes hard at feeding time (guppies, danios, most barbs); think peaceful nano stuff like small ember-type tetras, pencilfish, and tiny shrimp if you do not mind some baby shrimp snacks.
- Use a tight lid and block filter intakes - these fish are small enough to vanish into gaps and sponges, and they will jump when spooked.
- Breeding is scatter-spawning in plants: give them thick moss and feed heavy on live foods, then pull adults or move the moss to a rearing tub because they will pick off eggs and fry.
- Watch for slow starvation and wasting even when they look like they are eating - if food is not small enough or they are being outcompeted, they just fade over a couple weeks.
Compatibility
Good Tankmates
- Tiny, calm micro-schoolers like ember tetras or green neon tetras - they hang midwater, dont bother the lampeyes, and the whole tank feels busier without anyone getting pushed around
- Small rasboras like chili rasboras or harlequins (in a smaller tank, stick to the tiny ones) - same vibe: peaceful, fast enough, and they wont intimidate these little guys
- Corydoras (pygmy, habrosus, or regular small species) - great floor crew, totally ignore the lampeyes, and the lampeyes stay up top doing their thing
- Otocinclus - awesome with them in planted setups, super mellow algae pickers that dont compete for the same space
- Small, peaceful shrimp-friendly fish setups like with Amano shrimp or nerite snails - lampeyes are so small-mouthed theyre usually a non-issue, especially with plants and hiding spots (baby shrimp are still baby shrimp though)
- Gentle dwarf cichlids like Apistogramma or German blue rams - only if the tank is roomy and planted; the lampeyes stick to the top, just watch any spawning aggression near the bottom
Avoid
- Anything bigger that sees them as bite-sized snacks - angels, gouramis with attitude, larger tetras, most medium cichlids - if it can fit one in its mouth, it will try eventually
- Nippy fin-biters like tiger barbs or serpae tetras - theyre quick little guys but they get stressed when the tank has constant chasing and pecking
- Aggressive or hyper-territorial fish like bettas (some are fine, many are not) and most cichlids beyond the small dwarf types - lampeyes do best when nobody is patrolling the tank
- Predatory oddballs like puffers - theyll either harass them to death or just eat them, and the lampeyes cant really defend themselves
Where they come from
Goulding's lampeye (Fluviphylax gouldingi) is one of those tiny South American oddballs that makes you wonder how something that small even survives in the wild. They come from slow, plant-choked waters and shallow margins where the current is gentle and the cover is thick. That habitat vibe matters, because they behave like a fish that expects to be one missed shadow away from becoming lunch.
These are true microfish. Most losses I see with them come from people treating them like "small tetras" instead of "tiny live food hunters that hate sudden change."
Setting up their tank
If you want to keep F. gouldingi, think "quiet, mature nano" not "freshly cycled show tank." I had the best results in a heavily planted setup that had been running a while, with gentle filtration and lots of micro-hiding spots.
- Tank size: 5-10 gallons works, but bigger is easier for stability. A 10 gallon is my sweet spot.
- Filtration: air-driven sponge filter or a very gentle HOB with a prefilter sponge. You do not want them getting pinned to an intake.
- Flow: low. They spend a lot of time near the surface and in calm corners.
- Cover: floating plants (salvinia, frogbit), fine-leaf plants (guppy grass, hornwort), moss, and leaf litter if you like that look.
- Lighting: moderate. Too bright and they stay hidden unless you have a lot of floaters.
- Lid: yes. Tiny fish can jump, and evaporation swings can mess with such a small tank.
Water-wise, stability beats chasing a perfect number. Soft to moderately soft freshwater is what I'd aim for, slightly acidic to neutral is fine. Temperature in the mid 70s F (around 24 C) keeps them active without feeling like you're cooking them.
Skip big water changes. With these, I do smaller changes more often. A sudden swing (temp, TDS, pH) is a fast way to lose them.
What to feed them
Feeding is where most people hit the wall. Their mouths are tiny and they key in on moving food. Mine ignored a lot of dry foods at first, and even when they did take them, they did better on small live or frozen stuff.
- Best staples: live baby brine shrimp (newly hatched), microworms, walter worms
- Great extras: daphnia (small), cyclops, vinegar eels, moina (if you can get it small enough)
- Frozen: cyclops and baby brine work well, but thaw and swirl it so it drifts around
- Dry: very fine powders or crushed micro-pellets can work after they're settled, but don't bet the farm on it
I feed tiny amounts 1-2 times a day rather than one big dump. If you can see food hitting the bottom untouched, it was too much or too big.
They are fast little pickers once they are confident. If you're running a planted tank with microfauna (infusoria, tiny copepods), you'll notice them grazing between meals too. That helps a lot with new fish settling in.
How they behave and who they get along with
They are peaceful, a bit shy at first, and way more fun in a group. The "lampeye" look shows best when they feel safe, and that usually means numbers and cover. In small groups they can act skittish and disappear any time you walk by.
- Group size: I'd start with 10+ if you can, in a tank that can handle it
- Tankmates: only other calm micro fish and tiny shrimp-friendly species
- Avoid: anything that can fit them in its mouth (most fish), and anything pushy at feeding time
Personally, I like them in a species tank or with very gentle companions like small rasboras (if you keep similar water), tiny otocinclus in a mature tank, or just a shrimp and snail crew. Even "peaceful" community fish will outcompete them for food, and then you end up with skinny lampeyes that slowly fade.
Watch feeding time. If you keep them with anything else, you need to make sure the lampeyes are actually getting food. They can look fine for a while, then you notice the bellies are flat and numbers start dropping.
Breeding tips
Breeding is doable, but it is fiddly. They tend to scatter tiny eggs in fine plants and moss, and the adults will pick off eggs and fry if they find them. If you want a decent yield, you need to either move adults out or give the eggs a place to fall where adults cannot reach.
- Spawning media: java moss, spawning mops, guppy grass clumps
- Method: condition adults on live foods, then move a small group into a breeding tank with moss
- Egg safety: use a mesh-bottom breeder setup or remove adults after a few days
- First foods: infusoria, vinegar eels, then baby brine shrimp as soon as they can take it
If you run a packed moss tank and never vacuum it hard, you might get "surprise" fry. The trick is keeping the tank stable and always having tiny foods available.
Common problems to watch for
Most issues with Goulding's lampeye are not weird diseases. They are "nano tank" problems: water swings, starvation-by-competition, and stress from being kept too exposed.
- Sudden die-offs after a water change: usually temperature/TDS swing or chlorine/chloramine slip-up
- Slow thinning and hiding: not enough appropriately sized food, or tankmates are stealing it
- Getting sucked into filters: intake not covered, flow too strong
- White spot/ich after purchase: stress plus unstable temps, especially in small tanks
- Mysterious losses in new setups: tank is too "clean" (not enough micro-life), or the tank is not mature yet
Do not treat them like disposable test fish for a new nano. They really reward patience, but they punish rushed setups and big parameter swings.
If you keep them in a stable, planted tank, feed small live foods, and keep the vibe calm, they are surprisingly tough for such a tiny fish. The hard part is getting your routine dialed in so they are never stressed and never hungry.
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