Confused... annuals or non-annuals

[adr7]

Hi all,
How do i differentiate between annuals and non- annuals? What difference do they have? Share your knowledge...
Thanks

[whuntley]

Most of the killies of South America are annuals, except for those still being called Rivulus.

All Nothobranchius species are annuals.

Most Fundulopanchax are semi-annuals or annuals, but you may need to ask or look them up to find out.

The distinction is that they come from areas that have rain cycles that allow their habitats to dry out nearly every year. As a result, they have evolved a survival strategy that allows their eggs to rest in the mud until the rainy season returns. This "dry" diapause for the eggs is the unique thing distinguishing them from the plant spawners or crevice spawners.

Non-annual eggs often can be kept in damp peat, and shipped that way. The extra oxygen seems to retard hatching a bit, so some folks use this as a way to get all of a batch of eggs to mature and hatch the same day. Most Aphyosemions will hatch in the peat if left too long. Some Fp. also can be uncertain and will hatch in the peat if left very long.

HTH

Wright

[stormhawk]

Hello Adrian, its real simple to separate them. Look through the main site (www.killies.com) for pictures of some annuals and non-annual species.

One differentiates them by their methods of reproduction. Annual fishes come from temporary bodies of water, much like a pond that fills up after heavy rains and dries up during the dry season when temperatures rise up. These fishes have evolved a method of laying eggs that basically "sleep" in the mud or substrate, depending on the nature of the earth at the bottom of the pond. These eggs can undergo a hibernation period from anywhere near 6 weeks to almost a year and even more. The fry usually develop once the rains are near and hatch out within hours of the first rains. Some eggs don't hatch immediately, they hatch at a later date. This is called diapause whereby the fry hatch out later just in case the initial rainfall was a freak storm and they don't end up dying should the ponds dry up quickly. Only when the ponds have filled up and are in no danger of drying up with frequent rainfall will these fry succeed to survive to adulthood. The fry of annual species usually grow up much faster than non-annuals due to the temporary nature of their habitat. The parents of course, don't survive to see their babies hatch out weeks or months later. In the home aquarium however, some species can survive for years in captivity whereas others don't make it past their first 3 months..

Non-annual killies come from bodies of water that do not dry up for most of the year. These fishes lay eggs that develop very quickly in water, usually within 2 weeks of being laid some should hatch out very fast. Annual fishes usually produce fry that are slow-growing in comparison to the annuals. Some species can take months to grow up to adult size and can take even longer to sex out. These species are usually long-lived.

And there are the semi-annual killies that can adapt to either situation. The best examples would be the Fundulopanchax killies.

Examples of Annual Killies :

Simpsonichthys species
Nothobranchius species

Examples of Non-Annual Killies :

Aphyosemion species
Aplocheilus species
Rivulus species

[adr7]

Thanks guys