Yellow-striped cardinalfish / Orange-striped cardinalfish
6Scientific name: Ostorhinchus cyanosoma
6Pronunciation: Oss-tow-rinch-uss sigh-ann-oh-sow-mah
6Maximum size: 8cm maximum but 6.5cm more likely for captive individuals. 6Distribution: Western Pacific including Philippines and Indonesia.
go off foraging when the lights go out, but this diurnal socialising often occurs beneath overhangs and in caves and often inconveniently out of sight of the aquarist.
For some aquarists these looser aggregations are still something that they aspire to keep and there are other good reasons for housing these fish in numbers; for example, nervousness will be high if the fish are kept singly or in pair.
Conversely, there are instances of groups of Ostorhinchus cardinalfish being observed bickering and picking on one another until, in extreme cases, an individual dies. This can happen repeatedly until the group dwindles to one or two individuals. This could be due to inadequate numbers being stocked in the first place, or perhaps even issues with the health of a single fish that’s then driven away by the healthier fish in the population.
Specimen Selection
Once a decision to acquire a group of Ostorhinchus cardinalfish has been made it is essential, wherever possible, to apply the same selection criteria one might apply to a tang or dwarf angelfish to every individual. Is it feeding? How does it look? Any signs of stress?
The reason we do this is because these same selection criteria might not have been applied further up the supply chain, and this is wise to take into consideration when you’re purchasing any marine species.
Often the only selection at a collector, exporter or wholesaler level might involve the selection of those fish that can be easiest caught with a swoop of a net. Unfortunately, not all individuals handle being collected and shipped in the same way and losses can happen. And while there are dependable captive bred specimens out there, most notably supplied by Ora Farm in Florida, Ostorhinchus only represents a small part of its business and at present the demand massively outstrips supply in the US alone.
As an end consumer buying for your tank, it does fall on you to select the best fish available where you have that option. It’s time consuming and often frustrating to follow individuals within larger groups and
assess their condition, or to single out non-feeding fish in a shoal, but it’s worth ensuring that you take home only the healthiest specimens to make up a shoal of your own.
Breeding
Ostorhinchus cardinalfish are paternal mouthbrooders just like the other well-known members of the Apogonidae. However, with this genus the time the male holds the egg mass in his mouth until the larvae hatch can number only a few days, resulting in offspring that are much smaller than with other cardinals, and therefore much more demanding to raise.
Even Ora Farm, with all its years of expertise and state of the art facilities, describes Ostorhinchus as challenging to breed.
This is due in part to the low fecundity of the parent fish, but also the demands of raising especially small larvae that often refuse take the even tinier foodstuffs, meals that would normally be offered to others species’ larvae at the same size. Couple this with the kind of low customer demand that doesn’t necessarily inspire the investment required to upscale production and, for the time being at least, we can see why captive bred individuals might remain elusive.
Still, Ostorhinchus is a diverse genus containing many beautiful species that may make for ideal aquarium fish with particular suitability for the coral-rich reef aquarium.
But as we’ve looked at, specimen selection is a vital ingredient of success with these fish and, for some, adding a number of fish at the same time can result in a display as close to a shoal as it’s possible to get in a saltwater aquarium, but only in a system sympathetic to their needs; peaceful and with regular feedings of suitably sized and nutritious diets. They might not be the most famous of the cardinalfish but they are up there with the coolest.