Freshwater SNAGS: Stay at home dads of the freshwater realm?

Posted on Posted in finned

Creating a suitable home and raising a healthy family is traditionally the woman’s job. But … this isn’t always the case in the world of fish.

I am lucky enough to live near an exceptionally healthy population of Eel-tailed catfish (Tandanus tandanus). Tandans were once wide-spread across eastern Australia, but populations have declined dramatically over the past decades mainly due to flow regulation.  Near Mackay QLD, the male tandans amaze us each spring with their astonishing engineering efforts, undertaken to impress the fussy females.

A close-up of a carefully constructed tandan nest

As flow levels ease and the water warms up, male tandan hormones skyrocket and they become increasingly active. In a matter of days ‘nests’ appear in the stream beds.  These circular nests are 1-2m wide and consist of large rocks and pebbles and small, brightly coloured stones, all delicately collected by the male. Nest material is strategically nudged into place to form the most seductive yet practical nest to attract females.

A series of Tandan nests in a freshwater stream

Constructing the nest is only half the battle. The males remain in their nests constantly preening, clearing debris, chasing away male competitors and of course waiting for female company. Female tandans casually swim around inspecting the local nests, depositing eggs in those which are up to scratch. Once the eggs are deposited the male must tend to them, ensure the nest stays clean and well-oxygenated, and chase off any predators.

Footage of the male tandan patrolling his nest

After a few weeks the larvae leave the nest, and the mans work is done. Until next year.

So if you notice a large, saucer-like depression, filled with clean, shiny rocks in the middle of a stream – stay close by and you may see a male tandan hard at work guarding his brood.

Leave a Reply

Your email address will not be published. Required fields are marked *