Largescale chela

Where they come from

Largescale chela (Chela macrolepis) come from South and Southeast Asia, where they spend a lot of time in moving water - rivers, streams, and open stretches where there is current and plenty of oxygen. They are built for that life: streamlined, fast, and happiest cruising in the top third of the tank.

Setting up their tank

Give them length more than height. These fish want to sprint, not hover. A long tank with uninterrupted swimming space makes a bigger difference than fancy decor.

• Tank size: I would not do them in less than a 4-foot tank. Bigger is calmer.
• Group size: keep a proper group (8-12+). Small groups get skittish and bicker more.
• Flow and oxygen: moderate to strong flow plus lots of surface movement. They perk up in it.
• Filtration: oversize it. They are active, eat a lot, and appreciate clean water.
• Lid: tight-fitting. They jump, and they do it with purpose.

Decor-wise, think 'edges for cover, middle for racing.' I like plants or wood pushed to the sides and back, leaving the center open. Floating plants can help them feel less exposed, but do not smother the surface because they also like that oxygen-rich top layer.

Water numbers are not the whole story, but stability matters with these. Aim for neutral-ish water and keep it consistent. They handle a range if you do not swing things around with big parameter jumps.

What to feed them

They are surface-oriented micropredators and opportunists. Mine did best when I fed like I was feeding fast danios: small items, varied, and offered in a way that spreads the food out so everyone gets some.

• Staples: quality flakes and small floating pellets (they take midwater food too once it sinks).
• Frozen: daphnia, cyclops, brine shrimp, chopped bloodworms (not as the only food).
• Live treats: live daphnia or baby brine shrimp really flips the 'on' switch.

Feed smaller portions 1-2 times a day instead of one big dump. They hit food hard and fast, and slower fish can get nothing if you are not watching.

How they behave and who they get along with

Chela macrolepis are schooling fish, and they act like it. In a good-sized group they cruise, spar lightly, and look confident. In a too-small group they get nervous and spend more time bolting around and slapping the glass.

They are generally not bullies, but they are intense. Their speed and constant motion can stress calmer fish. Also, anything tiny that hangs near the surface can look like a snack once the chelas are grown.

• Good tankmates: other fast, current-loving midwater fish (bigger danios, larger rasboras), robust barbs, loaches that keep to the bottom, many peaceful rainbowfish in larger tanks.
• Use caution: slow gouramis, fancy long-finned fish, shy tetras, and surface-dwelling nano fish.
• Avoid: fish small enough to fit in their mouth, and aggressive fin-nippers that will turn the tank into chaos.

Breeding tips

Breeding them in a community tank is a long shot because adults will happily eat eggs and tiny fry. If you want to try, set up a separate breeding tank and treat it like a project, not a lucky accident.

• Conditioning: heavy feeding with live/frozen foods for a couple weeks, plus frequent water changes.
• Spawning setup: fine-leaved plants or spawning mops, and a way to keep adults off the eggs (mesh floor, marbles, or pull the adults right after).
• Water: slightly cooler fresh water change can trigger spawning in some riverine cyprinids.
• Raising fry: start with infusoria or very small foods, then move to baby brine shrimp as soon as they can take it.

Common problems to watch for

Most issues I have seen with largescale chelas come from three things: not enough swimming room, not enough oxygen/flow, or stress from being kept in a small group.

• Jumping: usually triggered by sudden lights, chasing, or spooking. Lid and a calm setup are your best defense.
• Nose rubs and split snouts: they hit glass when startled. Give them space, keep the front area clear, and avoid sudden movements around the tank.
• Wasting away after purchase: often internal parasites or just shipping stress. Quarantine, feed a variety, and watch who is not keeping weight.
• Ich and other stress diseases: show up fast in skittish schooling fish. Stable temps, clean water, and not overstocking go a long way.
• Gill issues: if they hang at the surface gasping, think low oxygen, high temperature, or dirty water first, not 'they like the top.'

If you treat them like 'bigger danios that really need a lid' you will be on the right track. Give them room, current, a real group, and regular water changes, and their whole demeanor settles down.