Are "annual" killies really annual?

[Piscesgirl]

I'm sorry if this sounds like a stupid question -- but I was wondering if Annuals were "annuals" because of their environments drying up or if they truly will live only one year? Will they then pass away of old age?


I suppose I have another question as well -- It seems they are all sold as pairs. Does anyone often sell females only, etc?

Thank you! (again, sorry if my questions sound stupid)

[whuntley]

I'm sorry if this sounds like a stupid question -- but I was wondering if Annuals were "annuals" because of their environments drying up or if they truly will live only one year? Will they then pass away of old age?


I suppose I have another question as well -- It seems they are all sold as pairs. Does anyone often sell females only, etc?

No, many can live longer than a year. My personal record was a peruensis that was well over three years old (and had been through three owners) when he kicked off. Killies, even annnuals, have lifetimes similar to many other aquarium fish. Don't tell the stores, or they will want to stock them, since 99% of what they sell lasts less than a month, anyway.

I first worked with N. guentheri back in the late '50s. My neighbor, Stan Weitzman, wanted to study the aging process. A prof. in Washington was using the spawning deaths of salmon to study it. Stan was an anatomist and had no desire to do a complete microtoming and cellular inspection of 30 lb. fish He thought GUE would be a nice size to slice up and really examine, 100%.

Unfortunately, their reputation for living less than a year was overblown and healthy fish refused to die on schedule. Of such things are reseach projects ruined.

Since we have mostly kept them from the stores, selling as pairs has become standard as it is silly to pay big bucks (sometimes two or three!) for a fish that is only going to be an ornament for a few years. :^)

[Still need that tongue-in-cheek icon!]

Seriously, killifish do not lend themselves to fish farming and we have to do it to keep such a large variety of species going.

Wright

[stormhawk]

Deborah, its okay to ask questions as long as they're understandable to the reader.

For annual fishes, why they are called so is because of their reproductive nature. In their natural habitat, the bodies of water like ponds in which they inhabit, undergo periodic changes and dry up during the dry season. They have evolved to live in such a habitat by growing up fast and laying enough eggs into the bottom of the ponds before it dries up. The remaining eggs lay dormant and develop until the next rains come and start to fill up the pond again. It is during this time that the fry hatch out from the eggs and start feeding on the abundant microfauna that also springs back to life after the rains. Its very much like spring time when some hibernating animals wake up from their deep sleep during winter.

Some annuals like Simpsonichthys constanciae, can live for several years in our aquariums under good conditions but some are not able to do so, like Nothobranchius furzeri, which I recall lives only for 3 months or so before the adults die. The longevity of an annual fish very much depends on the species and in some parts, on their diet and the care they receive in captivity.

Most are sold as pairs but very seldom as females only because the females are usually drab in colour that some buyers may just think they're nothing more than female mollies. They're usually sold as pairs or trios and occasionally as males only if the breeder will only release his excess males. Only rarely will one sell just females.

Hope I've answered your questions.

[stormhawk]

Wright, some species of killies have been subjected to large scale farming in SEA. For example the AUS and ANN. Fish farming of killies however has been more or less confined to species that have been easy to breed and raise in an aquarium setting. I can't imagine seeing a fish farm try to breed something like Aphyosemion hera or any species that produces a skewed sex ratio in mass numbers.

[Piscesgirl]

Yes, question answered -- thank you both very much!

I have a 20 gallon that is only plants right now - going to be the overflow for my 29 gallon shrimp tank. I thought a short-lived Killifish might work out well in the meatime -- especially since I have all kinds of worms in there that perhaps they'd enjoy. I don't feed live foods, but apparently the guy who gave me some malaysian trumpet snails does -- I poured the snails and a bit of substrate into the tank, and now....tons of worms



I wonder how hard it will be to find a male Nothobranchius furzeri would be in my area? Or, a single female...

[stormhawk]

They're pretty rare to come by. I'm not sure if the AKA has them but going by the size of the AKA there's surely a few that has them but be prepared to pay extra for rare fish.

[Piscesgirl]

Hmm, are there any other truly short lived, less rare ones then?

[TyroneGenade]

You can try fish of the Notho. kafuensis group. They only seem to live about 8 to 9 months. The black rachovii as well. I think the Plesiolebias of S. America are also short lived.

Oh, and the eggs don't nee a dry period of a lot of species. They can develop in water out of peat quite nicely.

tt4n

[Piscesgirl]

Thanks Tyrone -- I'll look around for those. I hate to try eggs because I won't know what to do with the rest if more than one is raised. I'm the sort that gets pets and then has to 'plan a college education' for them! So, nice to have some that aren't dependent for too long :P

[erikthur]

If I got it correctly, is not Tyrone in Italy to study Nothos because they are short-lived - as a model in ageing?
Earlier I wished I had an excuse to study killies in some way (I am a physician/radiologist - thought of annuals and geriatrics...) but finally got my Ph D by a thesis in mammography.
Another guy in Uppsala tried to use the gills of Fundulus heteroclitus in a kidney membrane study even if it's function was the opposite... At least I got some interesting killies from that project.

[stormhawk]

Oh, and the eggs don't nee a dry period of a lot of species. They can develop in water out of peat quite nicely.

Tyrone, which of the annual species has eggs that can develop in water out of peat? I've not heard of any so information on this matter would be appreciated. Thanks.

[whuntley]

My personal experience in water incubation is limited, so I can only contribute two species that I know will incubate without a dry diapause.

Nothobranchius korthausae is one, and Leptolebias (Or whatever it is this week) minimus is the other. I'm sure there are more, and you discover it when you keep them in a pretty planted tank with sand or gravel substrate and babies start showing up.

It is more speculative than direct experience, but I think many of the annual and semi-annual Fundulopanchax can water incubate under the right circumstances.

Wright

[Svein]

Tyrone, which of the annual species has eggs that can develop in water out of peat? I've not heard of any so information on this matter would be appreciated. Thanks.

I have hatch 3 litter with Fundulosoma thierryi in wather. The fish have put the eggs in Javamoss in the tank, and after a 2 months incubation period, the fries hatch.
Regards
Svein

[TyroneGenade]

About 2 weeks back I took about 15 N. rachovii eggs out of the peat and put them into a petri dish with water and some peat extract (anti bacterial agent). These are now eyed up and ready to hatch. To hatch, take them out and add fresh peat and an oxygen tablet. Bingo presto 15 fry... in theory.

As long as the eggs are not exposed to low oxygen conditions they will develop in water. If they are laid in peat that can turn anoxic (even anaerobic) then the eggs are stimulated to enter diapause. To get them out of diapause, dry the eggs on peat and the put them in water to develop. Development is 2 to 4 weeks at 25°C. It works equally well with furzeri.

tt4n