Blue Oxide Cardinalfish

Ostorhinchus compressus - The Blue Oxide aka the Ochre Striped Cardinalfish or Blue Eyed Cardinalfish is a striking and underrated reef species that is finally becoming more accessible thanks to aquaculture. With its clean horizontal striping and active, midwater behavior, it offers a different look compared to more commonly kept cardinalfish. Biota’s success in captive breeding this species means aquarists can now enjoy a fish that has historically been scarce in the hobby, with all the added benefits of being aquarium-raised.

In the aquarium, O. compressus does best when kept in small groups or shoals. Unlike many marine fish that show aggression toward their own kind, these cardinals are naturally social and display more natural, confident behavior when housed together. A group of three can be kept in tanks around 50 gallons or larger, while bigger shoals really shine in longer aquariums, especially those 6 feet or more in length. Providing plenty of rockwork and hiding spaces may seem counterintuitive, but it actually helps them feel secure and encourages them to spend more time out in the open water column.

This species is generally considered reef safe, though caution is advised with very small fish or shrimp, as larger individuals, which can reach around 4.5 inches in captivity, may view them as food. Feeding is straightforward, as captive bred individuals readily accept a wide range of foods. A varied diet of frozen meaty foods along with prepared options like pellets and gels will keep them in excellent condition. With their peaceful nature, schooling behavior, and adaptability, Ostorhinchus compressus makes a unique and rewarding addition to a well-planned marine aquarium.