Breeding the Lesser Spiny Eel (Macrognathus aculeatus)

Macrognathus aculeatus is a high-fecundity Asian spiny eel that has occasionally bred in aquaria, favouring floating-plant roots as a spawning site.

Overview

The Lesser Spiny Eel (Macrognathus aculeatus) is an Asian mastacembelid reaching about 38 cm TL, found in freshwater and brackish habitats across Thailand, the Malay Peninsula, Borneo, Indonesia and into Bangladesh, Nepal, India and Vietnam. It is a potamodromous, crepuscular and nocturnal burrower of medium to large rivers, lowland wetlands and peat areas, and is listed Least Concern by the IUCN (FishBase; Wikipedia).

Conditioning

FishBase reports high fecundity, with a minimum of 1,000 eggs, indicating a productive seasonal spawner. Conditioning relies on heavy feeding of live and frozen meaty foods over a sand substrate the eel can probe and burrow into, prior to a simulated wet-season change.

Breeding Setup

Unusually for a bottom-dweller, the roots of floating plants are favoured as the spawning site, so a setup should combine an open sand bed with dense floating cover. The species' potamodromous behaviour points to a rising-water, rainy-season cue (FishBase).

Spawning Behavior & Trigger

Spawning is linked to the wet season; FishBase gives the high egg count but limited behavioural detail, so the principal documented elements are the seasonal trigger and the floating-root spawning site. Soft, slightly acidic water with a temperature in the 23-28 C range matches the natural conditions (FishBase).

Egg & Fry Care

Eggs are deposited among floating-plant roots. With over a thousand eggs possible, ample plant cover is needed; specific incubation and fry-feeding timings for this species are not detailed in the available sources, so they are omitted here rather than estimated.

Common Challenges

Reliable sexing is difficult, the seasonal trigger must be recreated, and the burrowing adults may disturb or consume eggs. Because home spawnings are exceptional, this remains an advanced project.