Banded-tail glassy perchlet
Ambassis urotaenia
Also known as: Bleeker's glass perchlet, Bleeker's Perchlet, Bandedtail glassy perchlet, Glassy perchlet, Glassfish, Tail-mark glass perchlet
This is one of those see-through glassy perchlets where you can literally watch the organs shimmer when it turns-super cool in the right lighting. In the wild it hangs around river mouths and mangroves and cruises in groups, so it does best when you keep a little gang of them and give them some open swimming room.
The Banded-tail glassy perchlet has a transparent body with distinct dark bands and bright, reflective scales, enhancing its camouflage in aquatic environments.
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Quick Facts
Size
14 cm
Temperament
Peaceful
Difficulty
Intermediate
Min Tank Size
30 gallons
Lifespan
5-8 years
Origin
Indo-Pacific
Diet
Carnivore/invertivore - small crustaceans/zooplankton; in aquariums takes frozen/live foods and some meaty pellets
Water Parameters
25-29°C
7.5-8.4
8-20 dGH
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Calculate heater sizeCare Notes
- Keep them in a group (6+). A single banded-tail glassy perchlet usually turns into a nervous glass ghost that hides and eats poorly.
- They're brackish fish-run marine salt, not "aquarium salt." Aim around SG 1.005-1.012 (a refractometer makes this way less guessy), and keep it stable.
- Set the tank up like a mangrove edge: open swimming room with clumps of plants/roots/wood to break line-of-sight. They get bolder when they've got cover and can school in the open.
- Feed small meaty stuff: frozen baby brine, mysis, copepods, chopped krill, good micro pellets if they'll take them. They do best with 2 small feedings a day-big meals just foul brackish tanks fast.
- Tankmates: other calm brackish fish that won't outcompete them (small gobies, bumblebee gobies, mollies, smaller monos/archerfish only if the tank is big and feeding is dialed in). Avoid fin-nippers and anything that treats them like live snacks-these guys look bite-sized.
- Watch for "skinny but eating" and sunken bellies-usually they're getting bullied at feeding time or the food is too big. Target feed with a turkey baster if needed so the shy ones don't starve.
- Breeding can happen if they're settled: provide fine-leaved plants/mops and slightly warmer water, and you may see eggs scattered. Adults will absolutely pick off eggs and fry, so move the eggs or pull the adults if you want any babies to make it.
Compatibility
Good Tankmates
- Other brackish Ambassis/glassy perchlets (or your own banded-tails) in a little group - they're way more confident and bicker less when they've got a shoal
- Bumblebee gobies (Brachygobius) - same kind of brackish setup, peaceful vibe, they mostly mind their own business on the bottom
- Knight gobies (Stigmatogobius) *only if* they're similar size and you've got space/hides - they're usually fine, just don't cram the tank or they get pushy at feeding time
- Mollies (especially sailfin types) - they handle brackish great and are chill mid/top swimmers, just keep an eye that they don't outcompete the perchlets for food
- Figure-8 puffers (Tetraodon biocellatus) - not a fin-nipper like a lot of puffers, and in a roomy brackish tank they usually ignore the perchlets
- Scats/monos *when everyone's young and the tank is big* - they're not "mean," but they get big and boisterous, so it's more of a space/feeding competition thing
Avoid
- Anything properly nippy or hyper (tiger barbs, some danios, etc.) - glassy perchlets are pretty chill and will get stressed and shredded
- Big, hungry predators (arowana-types, big cichlids, large puffers) - if it fits in the mouth, it's eventually food
- Finny slowpokes in brackish (fancy long-finned stuff) - perchlets aren't usually the bullies, but mixed tanks like this tend to end with someone getting picked at or outcompeted
- Super-territorial gobies or mudskippers in tight setups - they can turn the whole bottom into 'their' turf and the perchlets just stop coming out
1) Where they come from
Banded-tail glassy perchlets (Ambassis urotaenia) show up around northern Australia and nearby coastal areas, hanging out in estuaries, mangroves, and tidal rivers. Basically: water that’s always a little “in-between,” where fresh and salt mix, and the flow and salinity change with weather and tides.
If you’ve only ever kept freshwater nano fish, the biggest mental shift is that these guys don’t want “a pinch of salt.” They want real brackish, measured with a hydrometer or refractometer.
2) Setting up their tank
Think of them as small schooling predators that like open swimming room, but still appreciate cover. I’ve had the best luck keeping them calm and visible in a longer tank (more horizontal space), with plants/structure breaking up sightlines.
- Tank size: I’d start at 20 gallons long for a group. Bigger always looks better with their schooling behavior.
- Group size: 8–12+ if you can. In small groups they get skittish and can turn nippy.
- Salinity: brackish, stable. Aim roughly around SG 1.005–1.010 as a practical range (match what your fish are already in and move slowly).
- Substrate/decor: sand or fine gravel; mangrove-style wood, rocks, and lots of visual cover.
- Plants: brackish-tolerant stuff like Java fern, Anubias (attached to hardscape), and sometimes Vallisneria depending on salinity.
- Flow/filtration: moderate filtration with decent oxygenation. They’re not fans of a dead-still tank.
Use marine salt mix (not aquarium “tonic” salt). Mix it in a bucket, heat/aerate it, then add it. A cheap hydrometer works, but a refractometer makes life easier and stops the guesswork.
Keep your lights a bit softer or give them floating cover if you want them out more. In a bright, bare tank they tend to hug the background and act nervous.
3) What to feed them
These are micro-predators. The number one mistake I see is offering only flakes and wondering why they look thin or ignore food. Once they recognize you as the food source they get bold, but they still love meaty stuff.
- Staples: frozen mysis, brine shrimp, chopped krill, daphnia, cyclops (size matters).
- Live treats (great for conditioning): baby brine shrimp, grindal worms, mosquito larvae (where legal/safe).
- Pellets: small sinking or slow-sinking carnivore pellets can work after they’re settled—train them by mixing with frozen.
- Feeding rhythm: small amounts 1–2x/day. They do better with “little and often” than one big dump.
If you’re keeping them with fast eaters (some monos, bigger gobies, etc.), the perchlets can get outcompeted. Watch at feeding time—don’t assume they’re getting their share.
4) Behavior and tankmates
They’re schooling fish with a bit of attitude. In a good-sized group they look fantastic—lots of “hovering” in midwater, quick little darts, and a pecking order that stays mostly harmless.
- Temperament: semi-peaceful. Can be nippy if cramped or kept in too small a group.
- Best tankmates: other brackish fish that aren’t tiny enough to be snacks and aren’t aggressive—think smaller gobies, bumblebee gobies in milder brackish setups, knight gobies only if tank is large and you know their personality, small monos if the tank is big enough.
- Avoid: very small fish/shrimp (they’ll hunt), long-finned slow fish (tempts fin-nipping), and big aggressive brackish species.
If you see fin-nipping, the fix is usually one (or more) of these: bigger group, more cover, or more space. Rearranging decor can also reset the “pecking order” drama.
5) Breeding tips
Breeding them is doable, but it’s not as straightforward as livebearers or cichlids. The adults don’t do any parenting, and the challenge is getting eggs/larvae away from hungry mouths fast enough.
- Conditioning: heavy feedings of live/frozen foods for a couple weeks.
- Spawning setup: a separate tank helps. Use fine-leaved cover (spawning mop, Java moss if your salinity allows, or synthetic mops) so eggs have somewhere to land.
- What to look for: males get more assertive and you’ll see chasing/hovering around the spawning media.
- Egg/larvae care: remove adults after spawning or pull the mop/media to a rearing tank. Start fry on infusoria/microfoods, then baby brine shrimp as soon as they can take it.
If you want to try breeding, have your tiny foods ready before you see any eggs. Fry don’t wait for you to set up a culture.
6) Common problems to watch for
Most issues I’ve seen come down to “new fish stress + wrong salinity + not eating.” Once they’re stable and feeding well, they’re pretty hardy.
- Salinity swings: topping off with saltwater instead of fresh (or vice versa) will mess with SG. Evaporation only removes water, not salt—top off with fresh water.
- Refusing food early on: try live or frozen foods first, then wean onto pellets later.
- Fin-nipping: usually too few fish, too small a tank, or not enough cover.
- Skin/gill irritation: often shows up after rough shipping or bad water. Quarantine helps a lot, and stable brackish water reduces stress.
- Ich/white spot: can still happen in brackish. Treat in a hospital tank if possible, and confirm your chosen med is safe at your salinity and for any scaleless tankmates.
Don’t “wing it” on salinity. Get a hydrometer or refractometer and actually measure. Most unexplained losses with brackish fish trace back to guessing.
Similar Species
Other brackish peaceful species you might be interested in.
African moony
Monodactylus sebae
This is that shiny, diamond-shaped "mono" that cruises around in a tight pack and looks like a little silver dinner plate with black bars when it's young. The big thing with African moonies is they're euryhaline-so they'll tolerate freshwater as juveniles, but they really shine long-term in brackish (and can be transitioned toward marine as they mature). Give them a big, open tank and a group, and they turn into nonstop, super fun midwater swimmers.
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Elongate mudskipper (pointed-tailed goby)
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This is that super-cool "mudskipper-ish" goby that mostly stays in the water, but will park itself in the shallows and periscope its eyes above the surface like it's keeping watch. It's an obligate air-breather from tidal rivers/estuaries, so it really appreciates shallow, brackish setups with soft mud/sand and gentle flow-more of a mangrove vibe than a typical community tank.
Feathered river-garfish
Zenarchopterus dispar
Zenarchopterus dispar is a surface-hanging halfbeak from mangroves and sheltered bays, with that classic long lower jaw for snapping up insects and other floaty foods. Males get those funky elongated fin rays (the "feathered" look), and they are livebearers, so once they settle in you can occasionally get surprise babies. Biggest thing with this fish is giving it calm water up top, room to cruise, and a tight lid because halfbeaks can rocket-jump.
Hairy pipefish
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This is a tiny, stick-thin pipefish that lives in seagrass and algae beds and uses its prehensile tail to hang on like a little underwater chameleon. The coolest part is the "hairy" fringing (little filaments) all over the body that breaks up its outline, and like other syngnathids the male carries the eggs in a brood pouch under the tail.
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Orange chromide
Pseudetroplus maculatus (syn. Etroplus maculatus)
This is that cute little Indian/Sri Lankan cichlid with the big black "shoulder" spot and a warm gold/orange glow when it's happy. It'll do the classic cichlid thing where it gets a bit pushy when breeding, but most of the time it's pretty chill-especially if you keep a small group. Super cool bonus: the parents actively tend the eggs and fry, and the babies even graze on the parents' skin mucus for a bit.
Spotted scat
Scatophagus argus
Spotted scats are those chunky, disc-shaped brackish fish with the peppered "polka dot" pattern that changes a lot as they grow. They cruise around in groups, eat basically anything you offer, and they're tough as nails-just don't fall into the super common trap of keeping them in straight freshwater long-term.
More to Explore
Discover more brackish species.
American flagfish
Jordanella floridae
Jordanella floridae is that little Florida native with the red-and-cream striping that really does look like a tiny flag once a male colors up. They graze algae like champs (especially stringy/hair algae), but they have a bit of attitude - give them plants and space so the bossy behavior stays manageable. Bonus: the male guards the eggs and will actively fan them, which is pretty fun to watch.
Atlantic Mudskipper
Periophthalmus barbarus
This is that wild little amphibious goby that straight-up climbs around on land like it forgot it was a fish. They've got big googly eyes, tons of personality, and they'll perch, hop, and patrol their territory-honestly more like a tiny crabby lizard than a "regular" aquarium fish.
Banded Archerfish
Toxotes jaculatrix
This is the fish that literally spits jets of water to knock insects off branches-watching one "take aim" is unreal. They're super aware of what's going on outside the tank and will even learn to beg and snipe food from the surface once they settle in. Give them height and some open swimming room and they act like little aquatic sharpshooters.
Barred mudskipper
Periophthalmus argentilineatus
This is one of those classic "walks around like it owns the place" mudskippers-big goofy eyes, climbs, hops, and spends a ton of time out on the mud when it's humid. In the wild it lives on intertidal mangrove/nipa mudflats and even shuttles between little pools and open air, hunting worms, insects, and small crustaceans. It's super fun to watch, but it really wants a brackish paludarium setup (not a normal aquarium).
Bumblebee goby
Brachygobius doriae
Brachygobius doriae is one of the classic "bumblebee gobies" - tiny, bottom-hugging little characters that perch on rocks and sand and stare at you like they own the place. They're at their best in a calm setup with lots of caves and leaf litter, and they really shine once you get them eating frozen/live foods reliably (they're slow, picky eaters). Also: they're one of the species that gets mislabeled a lot in shops, so it's super common to see them sold under the wrong bumblebee-goby name.
Bumblebee goby (Bumblebee fish)
Brachygobius xanthozonus
This is that tiny little goby with the bold black-and-yellow bands that likes to perch on the bottom and stare back at you like it owns the place. It's happiest in lightly brackish water with lots of little caves and sight-breaks, and it's one of those fish that often refuses flakes-frozen/live meaty foods usually flip the "yes, I will eat" switch.
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