Diancistrus Tetra

Hyphessobrycon diancistrus is one of the lesser-known members of the genus, originating from the acidic blackwater streams of the upper Rio Negro basin in Brazil. Its body is a translucent silver with a faint iridescent sheen, and a clearly defined dark blotch marks the mid-lateral line near the caudal peduncle. The overall appearance is understated but genuinely beautiful under appropriate lighting.

Keeping this species successfully requires dedication to water quality: very soft, acidic, and warm water is non-negotiable. Tannins from driftwood, catappa leaves, or alder cones replicate its natural environment and help maintain the low pH it requires. It is a sensitive fish not recommended for the casual beginner.

In groups of ten or more it forms cohesive schools and will display the best colouration. Feeding with fine foods — micro-pellets, small frozen invertebrates, and live nauplii — keeps it in peak condition.

Water: 24–28°C, pH 4.5–6.5, very soft (GH 0–6, KH 0–3); heavy tannin use essential. Tank: 60 L minimum; blackwater setup with botanicals, dark substrate, dim lighting. Feeding: Micro-pellets, baby brine shrimp nauplii, daphnia, micro-worms; avoid large dry foods. Breeding: Rarely bred in captivity; requires pristine very soft acidic conditions and live foods. Compatibility: Keep with other small, sensitive blackwater species; avoid boisterous tank mates.