Congo Ichthyborus

Where they come from

Ichthyborus congolensis is one of those Congo Basin oddballs that makes you realize how little of the hobby is actually "community fish." They come from big river systems in the Democratic Republic of the Congo where the water can be warm, moving, and full of driftwood, leaf litter, and patches of calmer backwater. Think predator-friendly habitat with lots of structure and plenty of things to ambush.

Setting up their tank

Give them space first, decorations second. These fish look manageable in the store, but they are built like a hunter and they use every inch you give them. I would not keep an adult in anything under a 4 foot tank, and bigger is honestly nicer because it spreads out aggression and reduces pacing.

• Tank size: 75+ gallons for an adult, 125+ if you are trying a group
• Flow: moderate to strong with calmer zones (they like to sit out of the current and dart through it)
• Filtration: oversized and easy to service (they are messy eaters)
• Cover: tight lid - they can spook and launch
• Lighting: subdued works better than bright, especially in a bare new setup

For decor, think "ambush lanes." A few big pieces of wood, some rock piles that cannot collapse, and open swimming space in front. Plants are optional. Tough plants can work if you anchor them well, but do not count on a delicate aquascape staying pretty once a big predator starts doing laps.

Water-wise, keep it stable and clean. Neutral to slightly acidic water is fine, warm mid-70s to low-80s F works, and they appreciate good oxygen. The real key is low nitrate and consistent parameters. They do not love "new tank syndrome" swings.

What to feed them

They are predators and they act like it. Mine did best on a rotation of meaty frozen foods and quality pellets, with occasional fresh items. The mistake I see is people trying to keep them on flakes or only one food and then wondering why the fish gets thin or moody.

• Staples: high-protein sinking pellets or sticks sized for predatory fish
• Frozen rotation: shrimp, silversides/white fish chunks, krill, mussel, bloodworms (as a treat)
• Occasional: earthworms (rinsed), chopped prawn, insect-based foods

Feed like you would a predator cichlid: not huge daily dumps. Adults do well with a good meal 3-5 times a week. If the belly is constantly bulging, you are overdoing it. If the head looks bony or the fish is always hunting the glass, bump the amount or frequency a bit.

How they behave and who they get along with

They are alert, curious, and very food-motivated. They will test anything that looks swallowable. Even if they ignore small fish for months, that does not mean they are "safe." One growth spurt or one night of hunting and the tank can look very different in the morning.

• Best kept: solo, or with robust tankmates that are too large to be eaten
• Risky: small to medium community fish, slow long-finned fish, shrimp
• Decent options: larger barbs, big Congo fish of similar size, sturdy catfish (Synodontis types), larger plecos
• Watch-outs: territorial bottom fish that will bicker over caves, and anything delicate that gets stressed by a fast predator nearby

They can be kept in a small group if you have a big tank and you start with similarly sized juveniles, but this is advanced-mode fishkeeping. You need lots of line-of-sight breaks, multiple feeding spots, and the willingness to separate fish if one becomes the bully. I have had them settle in, then suddenly decide one fish is the enemy after a water change or a redecorate.

Breeding tips

Breeding in home tanks is not common, and most hobbyists will never see it. They are not like easy-to-spawn tetras. If you are determined, you are basically trying to recreate a seasonal river fish situation with conditioning, heavy feeding, and a dedicated spawning setup.

• Conditioning: weeks of varied meaty foods and very clean water
• Setup: separate tank with dim light, lots of cover, and gentle flow
• Triggers: large water changes with slightly cooler water can sometimes kick off spawning behavior in river fish
• Reality check: you may need a proven pair and a lot of patience, and you might still get nothing

Common problems to watch for

Most issues I have seen with Congo Ichthyborus come down to stress from cramped tanks, unstable water, or diet problems. They are hardy once settled, but they do not forgive sloppy routines the way some beginner fish do.

• Refusing food after purchase: common if they are stressed - dim the lights, offer frozen foods, and do not keep bothering the tank
• Thin body despite eating: parasites are a possibility - quarantine new fish and be ready to treat if weight does not improve
• Cloudy eyes or fin damage: often from banging into decor during spooks or from tankmate scuffles
• Bloat/constipation: usually too much rich food too often - back off, add variety, and avoid feeding huge meals
• Aggression spikes: can happen after re-scaping or adding fish - have a divider or spare tank ready

If you keep the water clean, give them room, and feed like a predator (varied, meaty, not constant), they become really rewarding. You get a fish with tons of presence that actually watches you back.