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OVAL CHROMIS
Chromis ovalis (Steindachner, 1900)
These endemic damselfish are
often abundant, typically swarming high in the water to feed on
plankton. When not feeding they form dense schools near the bottom,
usually in the vicinity of crevices and caves. Adults are brassy
yellow-green but appear gray at a distance. Oval Chromis are most
plentiful above rocky or coral bottom at depths of about 20 to 130
ft, often mixing with the Threespot Chromis. The Oval Chromis dominates
the shallows; the Threespot Chromis is most prevalent in deeper
water, down to about 500 ft. Juveniles, common in the summer months,
are silvery blue with a bright yellow back and dorsal fin. Because
there are few blue fishes in Hawai`i, a school of young Oval Chromis
is an especially pretty sight. To 7 1/2 in. Endemic.
Reproduction:
During the spawning season (February
through May), many rocky bottoms in Hawai`i become alive with male
Oval Chromises establishing temporary spawning territories and clearing
nest sites within them. It takes them three or four days to do so.
Nests are usually in the open, spaced 3 to 9 ft. apart. At this
stage, males defend their territories only against other Oval Chromis
males. To attract a female, they usually take on courtship colors,
darkening and developing two broad blue-white bars, a blue-white
tail, and yellow pelvic and pectoral fins. They then perform a series
of "signal jumps," swimming rapidly up into the water
at an angle, then abruptly returning to the nest site. If interested,
a female will follow a displaying male to his nest and begin laying
transparent eggs, quivering as she does so. The male, also quivering,
follows to fertilize them. Every so often he swims up over the nest
to detect and drive away any potential intruders. It takes several
sessions each lasting from 30 seconds to several minutes for the
female to deposit all her eggs. Between sessions she moves slightly
away and rests. When done, she leaves and the male protects the
eggs, often driving away much larger fishes and even nipping divers
that get too close. The eggs hatch in about three days.
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