Borneo Loach

Buy this loach and you may not see it for a week. Pangio shelfordii spends much of its day buried in the substrate, which is why sand matters more here than almost anything else in the tank: coarse gravel can impede burrowing and carries a risk of injury. It reaches a standard length of 8 cm, and a footprint of 60 by 30 centimetres, working out at 54 litres, is enough for a group.

Wild fish live in slow forest streams, swamps and oxbows across Peninsular Malaysia, Singapore, Sumatra and Borneo, much of it peat-stained blackwater with readings as low as 3.0 or 4.0 on the acid scale. That tolerance shows in the published aquarium figures of pH 4.0-7.0 and 21-26 °C, far wider on the acid side than most community fish accept. FishBase publishes a warmer 24-30 °C band and a narrower pH window of 5.5 to 6.5.

Buy at least five. They are peaceful with everything, including each other, and in nature they gather in large aggregations, while a lone specimen tends to stay hidden permanently. Feed sinking dried food plus frozen or live bloodworm, daphnia and artemia, because the natural diet is mostly insect larvae and small crustaceans sifted out of the substrate. Leaf litter, driftwood and dim lighting complete the picture, and a tight cover is worth having, since most loaches jump when first moved. Protect filter intakes so that small fish cannot enter them.