While admiring the aquarium at Omaha’s Henry Doorly Zoo recently, we chanced upon a rather special moment in one of their reef set ups. It came as an opportune moment just as we were about to leave, when the eggs belonging to a pair of Acanthochromis polyacanthus decided to hatch. Needless to say, we took a short video clip of this event that is not very often seen.
Acanthochromis is a monotypic genus with only one member, A. polyacanthus. It bears the common name of Spiny Chromis, which stems from the greek word “Akantha” meaning thorn. It’s latin name directly translated means literally “spiny-chromis many-spines”. Where exactly the spines are, I’m not clear.
This species is actually extremely incredible for a number of reasons. Firstly, it is the only member of its family Pomacentridae whose larvae lack a pelagic stage. What this means is that the young hatch directly from their eggs and skip the free floating phase of their development completely. Secondly, it is one of very few marine species whose parents guard their fry, and they do this in a manner much like freshwater cichlids.
Acanthochromis form distinct monogamous pairs during breeding, and lay demersal eggs attached to hard substrate, like many Pomacentrids. The males aerate and guard the eggs until they hatch into large, swimming young. Much like Banggai cardinals, the young exhibits direct development, which makes rearing very easy. The males continue guarding the young up until their juvenile stage where they develop some coloration, and during this entire time they school tightly.
Unfortunately, although the juveniles are quite nicely coloured, the adults are dull and very unattractive. This large and black species would make for a good confidence builder in trying your hand at marine fish breeding, but would probably not make for very good looking pets. Either way, enjoy the video above of this seldom seen event, and watch how the young fish swim in a tight school with the parents in close proximity.