Because of its secretive nature, the reproductive behavior of pirate perch
(Aphredoderus sayanus, front cover) is poorly known. Early works report that
pirate perch build and guard nests. Others speculate that the female incubates
her eggs in her mouth, basing such speculation on three pieces of evidence: 1)
the pirate perchıs close relationship and anatomical similarity to the
mouthbrooding cavefish (Amblyopsis spelaea); 2) the observation that eggs
artificially stripped from a female pirate perch moved along a groove towards
the branchial cavity; and 3) the fact that a gravid female pirate perch had been
found with three eggs in its branchial cavity (the eggs were not identified as
to species). Separate accounts of aquarium spawnings by Ray Katula and John
Brill, published in American Currents, did not mention any evidence of branchial
egg retention. Although neither author actually witnessed the spawning act, both
reported that a nest, or depression, had been fanned in the gravel.
Now a scientific paper published in the December 1999 Journal of Freshwater
Ecology reports that pirate perch do not appear to be branchial brooders;
instead, the species releases adhesive eggs over leaf litter and woody debris.
Five adult pirate perch were collected from the wild and maintained in a
well-aerated 30 liter (8 gallon) aquarium with leaf litter and woody debris to
simulate natural habitat. The tank was kept in a room with restricted traffic
and an unshaded window to simulate the natural photoperiod. Water temperature
was 17-19°C (63-66°F). The fish were fed live amphipods.
The five pirate perch remained inactive in the tank until the first week of
March, when numerous eggs were observed. The eggs floated and drifted until they
become attached to any surface with which they came in contact. Eggs were not
observed being transferred to the branchial cavities. Nor were eggs observed
being fertilized by the males, which begs the question: Would pirate perch,
assuming for the sake of argument that they are mouthbrooders, attempt to brood
eggs that are unfertilized?
The aquarium experiment confirmed that pirate perch spawn fairly early in the
year, from February to March, presumably to avoid interspecific interactions
with other larval fishes. Aquarists willing to tackle spawning this odd fish may
be wise to begin their efforts before winter turns to spring. (Our thanks to Jan
Hoover for supplying this paper.)
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