Iskenderun bleak
Alburnus kotschyi
Iskenderun bleak has a slender, elongated body with metallic silver scales and a distinct dark spot at the base of its caudal fin.
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About the Iskenderun bleak
Alburnus kotschyi is a freshwater bleak endemic to southern Turkey, known from the Seyhan and Ceyhan river drainages and coastal streams between Ceyhan and Arsuz (İskenderun Bay watershed). It is not a standard aquarium-trade species.
Also known as
Quick Facts
Size
16.3 cm TL
Temperament
Peaceful
Difficulty
Advanced
Min Tank Size
55 gallons
Lifespan
3-6 years
Origin
Western Asia (Turkey)
Diet
Omnivore - small insects/larvae and other tiny invertebrates, plus some plant/algae matter; accepts small frozen/live foods in captivity
Water Parameters
10-22°C
7-8.5
8-25 dGH
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Calculate heater sizeCare Notes
- Give them a long tank, not a tall one - they are nonstop midwater sprinters. A tight lid is mandatory because they jump when spooked.
- They are native to southern Turkey river drainages (Seyhan and Ceyhan) and related coastal streams; if attempting to keep them, prioritize high water quality and good dissolved oxygen via strong surface agitation/flow, and avoid warm, stagnant conditions.
- No species-specific aquarium social/behavior data was found in authoritative references; if kept, it is reasonable to house cyprinids in groups, but avoid asserting exact shoal sizes or fin-nipping without species-specific evidence.
- They are built for current: add a powerhead or river-manifold style flow, plus rounded stones and hardy plants tied to wood/rocks (think Anubias/Java fern) rather than delicate stems. Leave a big open lane for swimming.
- Feed small foods often - they do way better on multiple tiny meals than one big dump. Quality micro pellets, crushed flakes, daphnia, cyclops, and live/frozen brine shrimp keep weight on without bloating them.
- Tankmates: other coolwater, fast, non-bullying fish work (similar-sized minnows, dace, some loaches). Avoid slow fancy fish and long fins, and skip tiny shrimp or very small fry because they will get picked off.
- Watch for two classic issues: banged-up noses from panic dashes (fix with a calmer room, more cover on the ends, and a bigger group) and rapid breathing from warm water or weak circulation. They also hate sudden parameter swings, so do smaller, more frequent water changes rather than huge ones.
- Breeding is doable if you mimic seasons: a cool period, then a gradual warm-up and heavier feeding triggers chasing. Give them fine-leaf plants or a spawning mop, then pull the adults because they will snack on the eggs.
Compatibility
Good Tankmates
- Other small, peaceful schooling fish that like cooler, well-oxygenated water - think danios (zebra danios, leopard danios). They match the bleak's nonstop cruising vibe and nobody gets singled out.
- White Cloud Mountain minnows - same general temperament and they handle the brisk, clean water these bleaks look best in. Keep both in decent-sized groups so they stay confident.
- Small barbs that are on the chill side, like cherry barbs - they can share space fine as long as the tank is big enough and you are not mixing in known fin-nippers.
- Peaceful bottom crews like Corydoras (paleatus especially if you run the tank on the cooler side). They stay out of the bleaks' midwater lane and everybody just does their thing.
- Temperate, non-aggressive species that tolerate similar cool-water conditions and good oxygenation (choose tankmates based on matching temperature range).
- Small, calm suckermouth algae eaters like Otocinclus (in a group). They are non-competitive and the bleak will ignore them once they settle in.
Avoid
- Big predators or 'one bite and its over' fish - cichlids like oscars, large acara, or anything that treats small silvery fish as snacks. Bleaks are basically built like feeder fish to them.
- Nippy, pushy schooling fish like tiger barbs, serpae tetras, or anything that turns fin-nipping into a hobby. The bleak is fast, but constant chasing stresses the whole tank.
- Slow fish with long fins like fancy guppies, bettas, or long-finned gouramis. Bleaks are peaceful but very active, and the mismatch often ends in stress or fin damage from bumping and chasing.
Where they come from
Iskenderun bleak (Alburnus kotschyi) is one of those slim, fast cyprinids from the eastern Mediterranean side of Turkey. Think coastal rivers and streams that can run clear and cool in spots, then warm up and get pushy after rain. They are basically built for current and open water - always on the move, always looking for the next bite.
Most people get surprised by how "river fish" they feel in the aquarium. If your tank is calm and still, they look stressed and act twitchy.
Setting up their tank
If you want these to look good, you build the tank around swimming room and flow. They are not a "pretty aquascape centerpiece" fish - they are the aquascape's cardio test.
- Tank size: I would not bother under 40 gallons, and 55+ is way nicer once you keep a proper group.
- Footprint matters more than height. Long tanks beat tall tanks.
- Group size: 8-12 is where they stop acting jumpy and start schooling.
- Filtration: strong. You want turnover and oxygen, not a gentle trickle.
- Flow: aim for a noticeable current across the length of the tank. Powerheads or a river-manifold setup work great.
- Substrate/decor: sand or fine gravel with rounded stones. Leave a big open lane for swimming.
- Plants: pick sturdy stuff or keep plants to the margins. They will not "eat" plants, but they will bulldoze delicate stems just by being busy.
Lids matter. These fish jump. Not "might" jump - they will. Any gap around hoses or corners is an exit ramp.
Water parameters are less about chasing a magic pH and more about stability, cleanliness, and oxygen. I have had the best results keeping them in cooler-to-moderate freshwater with lots of surface agitation. If the tank feels a little too calm, add flow before you start fiddling with numbers.
What to feed them
They are active pickers in the water column. In my tanks they hit food hard, then go right back to patrolling. If you only feed big sinking pellets, you will watch them look confused while bottom fish get fat.
- Staples: quality small floating pellets or crisp flake that stays in the water column for a bit.
- Best conditioning foods: frozen daphnia, cyclops, baby brine, chopped bloodworms (not as the only food).
- Dry-to-frozen rotation keeps them in better shape than either one alone.
- Feed small amounts more often. Two small feeds beats one big dump for this species.
If you want tight schooling and good color, give them a "drift" feed: sprinkle a little at the upstream end so it sweeps across the tank. They light up and chase like they are in a river.
How they behave and who they get along with
Iskenderun bleak are not bullies, but they are intense. They zip around nonstop, and that constant motion can stress slow or shy fish. With a proper group they spend most of their time schooling, sparring lightly, and chasing food.
- Good tankmates: other fast, midwater river fish that like current (similar-sized barbs/danios), and sturdy bottom fish that can handle flow (some loaches, tough gobies depending on your setup).
- Avoid: long-finned fish, slow fancy goldfish-type behavior, timid species that freeze up, and anything small enough to be treated like live food.
- Also avoid: very aggressive cichlids. The bleak are quick, but constant harassment wears them down.
They can look "peaceful" in the store and then turn into little rockets at home. The difference is usually space and current. Give them both and they settle in.
Breeding tips
Breeding is possible, but it is not the kind of fish that casually drops fry in your community tank. In my experience you get the best chance by leaning into what triggers river cyprinids: seasonal change, lots of live/frozen foods, and a dedicated spawning setup.
- Condition adults for a couple weeks on heavier feeding (daphnia, baby brine, quality pellet).
- Slight temperature swing and bigger water changes can cue spawning behavior.
- Use a separate tank with strong aeration and flow, plus spawning mops or fine-leaved plants, or a gravel tray/mesh that lets eggs fall out of reach.
- Remove adults after spawning. They will eat eggs and tiny fry.
- Fry foods: infusoria/rotifers first if needed, then baby brine as soon as they can take it.
If you are trying to breed them, start with a bigger group rather than a pair. They act more natural in numbers, and you are more likely to have both sexes ready at the same time.
Common problems to watch for
Most problems with this fish are "environment" problems, not mysterious diseases. They are sensitive to stale water and low oxygen, and they do not hide discomfort well - they just keep darting until they crash.
- Jumping: number one cause of sudden losses. Tight lid, block gaps, keep water level a bit lower if needed.
- Oxygen/flow issues: rapid gill movement, hanging near the surface, or acting panicky can mean the tank is under-aerated.
- Skinny fish in a group: they are fast eaters, but some individuals get outcompeted. Spread food across the surface and feed in two spots.
- Ich after purchase: very common with wild-caught/transport-stressed cyprinids. Quarantine if you can, and do not keep them in a cold, stagnant quarantine tub.
- Banged-up noses/fins: usually from spooking into glass. Dark background, floating cover at the edges, and a settled group size helps a lot.
If you see them gasping at the surface in a tank that tests "fine," do not wait. Add air and flow immediately, then check for clogged filter media and dead spots. These fish can go from "looks OK" to losses fast when oxygen drops.
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