It was first suggested that the migration of the anus in A. sayanus was to facilitate gill brooding of its eggs, as is found in northern cavefishes (Amblyopsis spelaea) with similar morphological features. However it was noted that the space within the branchial cavity of A. sayanus is insufficient to hold an entire clutch of eggs (Katula, 1992). Pirate perch actually spawn in underwater root masses and use their forward facing urogenital pores to deposit eggs and release sperm into the floating canopy (Fletcher et al., 2004). Fletcher (2004) observed that, within an assemblage, pirate perch were often of distinct developmental stages, strongly implying that the eggs had been deposited and/or fertilized during multiple spawning events.
Male pirate perch guard nests from other males wishing to fertilize the eggs. These behaviors are aggressive and probably relate to selection pressures imposed by intense competition for fertilization success in group spawning (Fletcher et al., 2004).
Mating System: polygynandrous (promiscuous)
Spawning generally occurs in May in floating root masses parallel to water flow. Female clutch size is about 100-400, depending on body size; in a single root mass, up to 2000 total offspring were found to be present in a single nest. Female pirate perch thrust their heads and release their eggs into the root masses and males congregate there to fertilize them (Fletcher et al., 2004).
Breeding interval: Breeding occurs once yearly.
Breeding season: Spawning occurs during the spring.
Range number of offspring: 100 to 400.
Key Reproductive Features: iteroparous ; seasonal breeding ; sexual ; fertilization (External ); broadcast (group) spawning; oviparous
The extent of parental involvement in the rearing of pirate perch is debated. Some sources suggest that parents guard the nest until the larvae are a little less than a centimeter long (Forbes and Richardson, 1920). However, more recent papers suggest that there is no evidence of extended parental care (Fletcher et al., 2004).
Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Female)