Borneo Redfin Silver Shark Care Guide - Aquarium Setup, Diet & Breeding

The Borneo Redfin Silver Shark is a streamlined, silvery cyprinid with a torpedo-shaped body, a dark-edged dorsal fin and attractive reddish to orange coloration in the fins, particularly when the fish is settled and in good condition. Its reflective flanks can give it a shark-like appearance, although it is a true freshwater minnow relative than a marine shark or a close relative of the familiar Bala Shark.

This is an active, alert schooling fish that spends much of its time in open water. Groups move together confidently, changing direction quickly when startled, while mature individuals may become more assertive around food or preferred swimming areas. It is generally less aggressive than the common name might suggest, but its size and energy make it unsuitable for a small community aquarium.

In the wild, the species inhabits clear to lightly stained tropical waters with a current, plentiful oxygen and a mixture of open swimming space and marginal cover. Submerged roots, branches and aquatic vegetation provide shelter, while gravelly or sandy areas offer feeding grounds.

The Borneo Redfin Silver Shark remains relatively uncommon in the aquarium trade compared with better-known Asian cyprinids. Its combination of metallic coloration, red fins and vigorous schooling behaviour makes it an appealing choice for experienced fishkeepers with a spacious aquarium.

Cyclocheilichthys janthochir is native to the island of Borneo in Southeast Asia, including freshwater systems in Indonesian Kalimantan and Malaysian Borneo. It is associated with flowing rivers, tributaries and connected floodplain habitats.

A group of Borneo Redfin Silver Sharks should have at least a 300-litre aquarium, with a minimum footprint of about 120 × 45 cm; a longer tank is preferable for active adults. Use efficient filtration and strong circulation while leaving calmer areas for resting. A fine gravel or sand substrate, smooth stones, driftwood, roots and hardy plants arranged around the margins create a natural riverine layout, but the central area should remain open for swimming. Keep the aquarium securely covered because startled fish may jump.

Up to about 20 cm (8 in) in total length. Females are usually slightly deeper-bodied and may grow a little larger or heavier than males.

This species is an omnivorous opportunistic feeder. Offer a varied diet of quality sinking or slow-sinking pellets and flakes, supplemented with bloodworm, brine shrimp, daphnia, chopped earthworm and other suitable frozen or live foods. Blanched spinach, shelled peas, spirulina-based foods and other vegetable matter help provide balance, while small regular meals are preferable to allowing food to accumulate.

Borneo Redfin Silver Sharks are suitable for peaceful, robust community aquariums containing similarly sized, active fish. Good companions can include larger rasboras, peaceful barbs, danionins, rainbowfish, larger tetras and non-aggressive bottom dwellers such as sturdy loaches and medium-sized Corydoras. Avoid tiny fish that may be intimidated or swallowed, slow-moving long-finned species, delicate shrimp and highly aggressive cichlids. They should not be housed with fin-nippers or territorial fish that cannot tolerate their constant activity.

Borneo Redfin Silver Sharks are egg-scattering cyprinids that provide no parental care. Successful breeding is uncommon in home aquaria, but a large mature breeding setup can be prepared with soft to moderately hard, well-oxygenated water, dense fine-leaved plants or spawning mops, and a group of conditioned adults fed generously on live and frozen foods. Spawning is usually triggered by abundant food and a partial water change; remove the adults promptly because they may eat the eggs. The eggs hatch in a few days, with tiny fry requiring infusoria or another suitably fine first food before they can accept newly hatched brine shrimp.

Sexual differences are subtle. Mature females generally have a fuller, rounder body, especially when carrying eggs, while males tend to be slimmer and may show stronger colour in the fins during courtship or spawning.