When we speak about cardinalfishes within the reef aquarium hobby, most people relate to the classic Pajama Cardinalfish, Sphaeramia nematoptera, or the Bangaii Cardinalfish, Pterapogon kauderni, which have been popular fish for reef tanks of all sizes for decades now. Reefers love them for many reasons, such as having decent color, fitting into virtually any reef tank, being non-aggressive, easy to feed as well as a side bonus of being very easy to breed within a reef tank.
Even though these two species of cardinalfish fully deserve their popularity within the hobby, there are many other species of cardinalfish from the family Apogonidae that are equally interesting or as stunning as their distinct counterparts, and today’s focus is on the members from the genus Ostorhinchus.
Ostorhinchus is a genus of cardinalfish with roughly 90 species, found throughout the coral reefs, coral communities, and rocky shorelines of the Indo-Pacific regions, and often appear in small to large groups in the wild. Even though they are such a common fish throughout the reefs in the Indo-Pacific regions, only a handful of species occur frequently within the aquarium trade. However, the good news is that the members of this genus are relatively affordable, are easy to care for, and often settle into captivity fairly quickly.
Even though I would like to write about all the different species of cardinalfish from the genus Ostorhinchus, today’s focus is on two of my favorite species from the genus Ostorhinchus, the Yellow-striped Cardinalfish, Ostorhinchus cyanomosa, and the Ring-tail cardinalfish, Ostorhinchus aureus.
The Yellow-striped Cardinalfish was a bit easier to come by within the local aquarium trade from my hometown in Hong Kong, as I managed to get my hands on two wild collected juvenile specimens from Indonesia back in Skyland Aqua on July 2023, but was quickly left with one as one of them had mysteriously disappeared with a few days after introduction. However, the other one was able to instantly adapt to aquarium life and even started eating my homemade frozen food mix within 20 minutes after introducing it to my 20-gallon mixed reef tank.
When first introduced, it was relatively shy and often took cover in between my rockwork and SPS corals. As a juvenile, it displayed thick brownish stripes compared to now, as an adult, and displaying bright orange narrow stripes. And after being in my reef tank for 7 months now, it has fattened up and reached its adult size of more than 2 inches. It swims actively around the open areas of the tank as well as occasionally begging for food when I walk past the tank.
The Ring-tail Cardinalfish was very hard to come by for many reasons. Firstly, both species of “Ring-tail Cardinalfish”, Ostorhinchus fleurieu and Ostorhinchus aureus are rarely imported into the local aquarium trade as they are not considered popular or mainstream fish for stores to import and sell over here in Hong Kong. Secondly, even if they were imported into the local aquarium trade, both O. aureus and O. fleurieu are imported under the same name and are hard to differentiate when they are not showing their true colors as they look the same, like the ones in the picture below shows.
Despite being very rare in the aquarium hobby here in Hong Kong, both O. aureus and O. fleurieu are native to Hong Kong waters, with O. fleurieu, in particular, being one of the most common species of cardinalfish in the wild here in Hong Kong. They occur in many popular dive sites which are located further from shore and appear frequently in local fish markets as fishermen often catch them via hook and line.
I was able to get my hands on a juvenile Ostorhinchus aureus from Skyland Aqua again, which was most likely imported from Indonesia with a bunch of Ostorhinchus fleurieu and other Ostorhinchus aureus individuals. The Ring-tail Cardinalfish I got was like my yellow-striped cardinalfish, as it quickly started eating my homemade frozen food mix on the same day it was introduced into the system. And despite it showing signs of ich after adding it to my 20-gallon mixed reef, it overcame it with no issues at all. It has been in my tank for well over a month now and has been growing and coloring up nicely. It now displays a metallic orange-ish copper color along with two deep metallic blue stripes along its eye, which I really like.
Just like most of the other members from the family Apogonidae, cardinalfish from the genus Ostorhinchus make the perfect candidate for any reef tank. Not only do they show great color, but they are extremely hardy and are also relatively cheap. They do equally well in shoals or by themselves and do not require multiple feedings a day, which makes keeping them even more flexible. I’m really glad that they are actually getting more popular within the hobby now, as the more popular species like the yellow-striped cardinalfish are being captive-bred by ORA, which makes keeping these such beautiful fish even more sustainable. If you are looking for some hardy shoaling fish for your SPS tank or looking for a more uncommon candidate for your nano reef tank, try getting some of these fish as you won’t regret it!
About the author
Aiden Chong is a 16-year-old reef aquarium hobbyist from Hong Kong who started fishkeeping back in 2015. He has 3 years of reefing experience and describes it as his biggest passion. Aiden also does fish identification online and looks out for cryptic species within the local aquarium trade and local fish market. His favorite fish genera belong to Serranidae, Chaetodontidae, and Apogonidae. His favorite corals are Acropora and Tubastrea.
