Cardinalfish are colourful and characterised by two separate dorsal fins that are usually carried erect, large eyes and distinct markings of stripes or spots. Large eyes indicate that these fish are nocturnal and they are often overlooked by divers as they tend to congregate under low overhangs during the day. The identification of these fish is further complicated by the fact that many species look similar. Most species feed at night on benthic (sand-dwelling) invertebrates and zooplankton (microscopic animals and larvae that drift freely in the water column).
Cardinalfish are very interesting in that they are one of the few marine fishes that are mouth brooders or oral incubators. Generally males carry the eggs in their mouths although some species are incubated by the females. When a female is ready to spawn she approaches a male and if receptive they swim side by side in circles. The male then releases his sperm closely followed by the female who releases her eggs. The male then sucks the eggs into his mouth and carries them until they hatch.
Due to the fact that the fish cannot eat during the incubation period and also that the eggs are growing larger it’s quite common in summer to see really skinny Cardinalfish whose cheeks are swollen up. There are approximately 250 species worldwide of which 53 are likely to be found in Southern Africa. The photographs are of the Sea Urchin Cardinalfish – Siphamia mossambica. These fish are overlooked by divers as their red colour disappears underwater and no-one expects fish inside an urchin. So next time you dive take a torch and check out all the large black sea urchins.
Sodwana currently is warm during the day with max temps of about 26°C and min temps of 16°C. Water temp is currently 26°C. No current with 12-15 metre visibility. Swell is about 1.5 metres.
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