Tropical Fish Keeping - Aquarium fish care and resources

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Austin 06-16-2010 10:46 PM

Livebearer fry spine issues?
Hey guys, some of my livebearer fry have these bent spines they bend downward like a V but not as straight down as a V. Anyways, I was wondering what caused this. My guess is bad water quality... though the water quality in one of my fish tanks with one of the fry's bent spine is ok I think at least my 29g tank. It's happened in other tanks too and I do clean my tanks. Anyways, does anyone know what causes this??

Also I have another question on it. Should I... euthanize the ones that have this spine issue? It doesn't seem curable. I have TOO MANY baby fish and not enough spaces to raise them anyways. Idk if I should keep these ones since they won't grow up to be healthy anyways? :/

bettababy 06-17-2010 12:13 AM

The spinal defomity you are speaking of can be caused by a few different things. Yes, water quality is one of them. Also it can be caused by genetic defect, most often found when there is a large amount of inbreeding going on... so if your babies are mating and having babies, who are mating and having babies... that weakens their genetic strain and this could get to be more common in new fry. Another cause is over crowding. Many species of fish can experience the bending of the spine if they are cramped without enough space to swim freely. That is more common in large fish species kept in small tanks, but it can happen in most species.

The best thing to do is to euthanize the affected fish. These problems lead to other problems, such as an inability to swim properly, compete for food & territory, etc. and usually leads to an early death. Nobody will want to buy deformed fish, so hopes of taking them to a lfs or auctioning them off... not worth trying.

My suggestion to you would be to try to separate the fish, males in one tank and females and fry into another. As soon as the fry are sexable, usually by about 4 wks, move all males out to the male tank. This is the only way to get breeding under control. If you are having space issues already, it is only going to get worse, and with a lot of females age 6 wks or older, the population will continue to multiply every 30 days. Females can retain milt in the body, so each female is capable of having up to 3 spawns after having been away from all male fish. So the only way to control population is to keep male/female separated beyond the first 4 - 5 wks.

Austin 06-17-2010 01:11 PM

Thanks for the advice. I guess having about 30-50 fry in a 10g tank won't work. :/ but I have nothing else to do with them. I think I'll just stop trying to save all the fry in the main tank.

One question I have is that at about 4 weeks my fry are still not very large... I have some platy fry that are about 5 months old and FINALLY reaching almost full grown size. The males just developed their gonopodium within the last 2 weeks.

Not sure about the inbreeding being the issue. They were pregnant from the fish store but not sure if that's the issue...

Oh, also, how should I euthanize them? >_<

By the way, just so you know what happened with Rebecca, my black balloon molly... she got sick and even worse this time and ended up dying. :( None of my other fish have caught the disease that I know of.

bettababy 06-17-2010 02:04 PM

Over crowding can stunt growth, but it causes internal damage as well. The delay in development is likely due to the stocking numbers in your tank. Platys do have the ability to be dimorphic, which means that female fish can turn male later in life. This most often happens when the ratio of fish is primarily female or if an only male dies or is removed. It is nature's way of preserving the species. That could explain the late change in your platy.

There is a lot of debate about how best to euthanize a fish. My preferred method is still to freeze them in a small zip lock bag of tank water. The gradual cooling water temp causes them to get lethargic/sleepy and then they just don't wake up. If you use this method, let the fish stay in the freezer for at least 12 - 24 hrs to be sure they are completely frozen and not going to "wake up" once they thaw out. The whole baggie can then be thrown in the garbage.
Be careful if you choose to use clove oil, which seems to be the preference of many lately. Clove oil is very potent, and if other fish are exposed to it, it can cause death quickly. Clove oil is also very difficult to remove from containers, so be sure to use something disposable and to bleach repeatedly anything that you intend to reuse, until all odor of the clove oil is gone. I use clove oil during surgical procedures on fish, and because of its potency and difficulty in removing from any surface, I have tanks that are designated for that only. My last attempts to bleach a 10 gallon tank that was used with clove oil, took me 6 tries with straight bleach, drying between each, and I still was not able to remove it all. I finally gave up and cut my loss of the tank and returned it to my group of surgical tanks. As difficult as it was to remove from a glass tank, a plastic container is even harder. Also... use gloves while using clove oil, and be sure to use enough of it and to leave the fish in there long enough... you would need to watch for gill movement and time it 30 minutes after all signs of gill movement have stopped. For small guppy fry it shouldn't take much of the clove oil to do the trick but leaving them in there long enough will still be important.

The only other thing I can suggest for you is to get a much larger tank if you decide to continue breeding these fish, and plan to separate them as I mapped in my previous post. If you wish to cut down population naturally, allow the female fish to live in the community tank and thin out the decorations when you are expecting fry. This will allow the other fish to eat the fry, which they will do if they find them. Even the female will eat them if she can get to them.

Good luck to you.

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