A description of the pelagic embryos and larval stages of Lates niloticus (L.) (Pisces : Centropomidae) from Lake Chad, with a review of early development in lower percoid fishes

Abstract

Eggs and larval development of Lates niloticus from Lake Chad are described. The pelagic eggs, averaging 0–83 mm in diameter, are characterized by a large single oil globule and a narrow perivitelline space. Hatching occurs at a remarkably premature ontogenetic stage, 1-2 mm in length. Detailed descriptions are provided of subsequent larval development up to the earliest juvenile stages. The occurrence of buoyant eggs in freshwater and brackish-water species, particularly lower percoids, is reviewed and comparisons are made with marine forms. A marked tendency for the relative size of the oil globule to increase with decreasing salinity is related to hydrostatic function. Demersal eggs in freshwater lower percoids are also discussed. Larval development in L. niloticus is shown to be similar to related forms but differences are noted in the stage at which hatching occurs and the position of the oil globule.