Egg-care behaviour of Aequidens paraguayensis (Pisces, Cichlidae) in relation to predation pressure and spawning substrate

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Abstract
Aequidens paraguayensis is a cichlid fish with biparental care that spawns on a leaf taken from substrate litter and, after the eggs have hatched, broods the progeny orally. We tested the hypothesis that increasing predator density causes proportional changes in the frequency or duration of parental care activities, including moving the spawn. We predicted that at high predator densities, the parents would pick up the eggs and begin mouthbrooding earlier than usual to prevent egg loss.Increasing predator density led to greater parental sex-role differentiation, the males defending the spawning site while the females tended the eggs. Leaf tugging was performed by the females only and did not increase significantly with predator density. Pairs that spawned on a fixed substrate did not exhibit this sex-role differentiation.Predator density and type of spawning substrate did not affect brood survival or time between spawning and beginning of mouthbrooding. Hatching time is temperature dependent and parents apparently must wait for the egg membranes to break before picking up the hatchlings.

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