Hormone-generating Fish

[mikev]

It seems that in some cases an actively spawning fish may induce other tankmates into spawning; I've observed this happening in my tank and similar observations were made by others I've talked to. The mechanism may be a release of hormones into water.

This brings up the question: what would be the best "hormone-generating fish"?
The requirements are:
1. Cyprinid.
2. Ideally, 2"-3".
3. Spawns most of the time, or very easy to induce into spawning.
4. Hopefully, relatively common.
5. Not too aggressive; it is not important how it looks like.
(I would like to experiment a little).

Suggestions? (Two candidates that spring to mind are Zebra's and M.Praecox....but I'd like to try to locate the best option before experimenting....)

TIA for ideas.

 

[Lateral Line]

Zebra's would be the obvious candidate for me as they are difficult to stop spawning. Interesting project, got any references?

 

[mikev]

Zebra's would be the obvious candidate for me as they are difficult to stop spawning. Interesting project, got any references?

Thanks LL, If I had references, I'd not be asking you!

I'm fairly sure that this may work. In my tank, one day of unusually intense spawning activity from D.Hikari's led to a week of similar activity among loaches, not seen before (I have the loach part recorded, albeit not the Danio's)....
The other incident (not mine) involved Rainbows similarly affecting kuhlis. No recording of it and I was not there to see.

One more candidate suggested by a friend is Cherry Barbs. Any take on them? (I never kept them....and I have to admit I never kept Zebra Danios either...five other species but not them.) Among the fish I have now, Odessa Barbs are the ones who do it non-stop, but they also search for food non-stop...nothing can possibly be born in a tank with them.

 

[ollyhtafc]

White cloud mountain minnows spawn a heck of a lot also.

 

[Colin_T]

The bigger the fish the better as bigger fish will produce more hormones. Also the more fish that start breeding the more hormones will be released into the water.
I would use rainbowfish. They are a serial spawner and as such will chuck out eggs each day for months at a time. This will give you plenty of opportunity to see what happens with the other fish in the tank. You can also stop them spawning by seperating males and females for a few days. Then when you put them back together they breed even more prolifically and there is the potential for more hormones to be released by fish that have abstained for a couple of days.

 

[mikev]

Hmmm.... this sounds good, especially the ability to create bursts. Would specifically M.Praecox do? (I never kept them..actually always wanted to try).
The issue with size is that I'd like to try this in small tanks (10g or 29g), so non-dwarf rainbows would not work. The three rainbow species I have are all not suitable (M.Affinis -- too large, P.Furcatus -- too small, and newly arrived Dubs here are young fry. Praecox are just the right size...).

Incidentally, I had a confirmation of the hormone theory. All spawning in the tank stopped for four days. Yesterday, I was acclimating new fish until 3am, and somehow the light in the middle of night induced the Danio's. In the morning, the loaches were at it again. (D.Hikari is an ideal fish by size and compatibility but their spawning behavior is unpredictable...random infrequent bursts.)

 

[Colin_T]

M. praecox will be fine. They don't get much longer than P. furcatus but are deeper bodied and produce heaps more eggs. They breed in typical rainbowfish style and go for it every chance they get.

Lots of marine fish are stimulated into spawning by other fish breeding. You quite often see a couple of fish suddenly dash upwards and release gametes. Then over the next few minutes more join them and before long every fish in the area is going for it or eating the eggs. There are factors associated with getting them into condition (tide and lunar activity) but it is the hormones released by the first few pairs that sets everyone else off.

 

[mikev]

Thanks Colin,

This is very useful and your comment on the marine fish is appreciated -- I guess this means this idea may work.
I'll start looking for M.Praecox once one of the qtanks becomes available..tbh, besides the utility purpose, I always wanted to try them ( ).

 

[Colin_T]

The only problem I had with M. praecox was tank space. They are prolific breeders and we had a few tanks with fry in They also need plenty of vegetable matter in their diet so it's a good idea to offer them a vege flake (spirulina or something). Give them a try and who knows, you'll probably make some money from all the young they produce

 

[mikev]

Yes, I know what you are talking about...one of the tanks here has a bad case of Endler disease (I think I'm up to 5"/gallon already).

Not a danger with the bows...there is no such thing as "prolific" on loach substrate, present in the tank they will end up in

 

[Lateral Line]

loach substrate