The Puffer Forum

Lilgreenpuffer brought up a good topic, concerning bringing in new stock to keep long-term tank bred fish and inverts healthy.

The long-term hobbyists here are likely to know well the degeneration of most live-bearers and even many long-term captive bred egglayers. Few newer hobbyists have ever seen "real" sailfin mollies, really hardy guppies and a number of other such fish. How about the tanks of fancy Angelfish with multiple specimens in a crowded tank including individuals which should have been culled by the breeder?

I do keep my own strain of essentially wild-type guppies, not ever mixed with fresh stock. Mine are rather plain guppies, but hardy and free of Mycobacterium marinum. They are used as biofilter-holding fish in temporarily otherwise unoccupied tanks, dithers for newish and shy fish fry, and sometimes as live food. I keep these fish unmixed with "fresh" stock due the extreme difficulty in getting clean livebearers. I am also keeping one strain/species of shrimp which is not common in the trade, but which interests me. Surplus of those do get used as feeders for some breeding Cichlids. I also intentionally keep a line breed group of rainbows which are from the first shipment of that species to this country which had both males and females (earlier shipment had only males). Rainbowfish in the trade suffer from breeding errors and many are no longer pure strains, even if they are when collected from the wild - which is not always the case.

So there are two sides to those coins. Stocks can easily suffer from inbreeding with unintended selection of degenerate stock. Bring in "fresh" genes from only distantly related specimens can invigorate a strain. But out-crossing can also introduce less vigorous specimens that those being line-bred.

*nod nod*

Very important to find high-quality stock to maintain genetic health.

ETA: I've always dealt with this problem with my red cherry shrimp by following the recommended guidelines and adding new shrimp every six months, and I always purchase from or trade with a reputable seller/hobbyist with positive reviews from past buyers. It can get expensive, so sometimes instead of buying a $20-25 package of shrimp, I simply find another reputable hobbyist and offer to trade 10-20 shrimp (by mail or locally); another option would be to find a local hobbyist and split the cost of ordering new livestock. I find these people on the Planted Tank forum, since it's easy to figure out who has a good reputation for healthy shrimp and reliable business practices.

One time, maybe a year into my shrimpkeeping, and about a year and a half ago, I slipped up and didn't add new stock for maybe nine months. I wound up with a genetic disease and sterile shrimp. But when I learned my lesson and kept my stock - new and old - healthy, I started making a lot of money and getting great reviews on my shrimp packages, and I haven't had issues with health since then.

That is obviously the desired case, but is a major chore. Also, maintaining more than one tank of whatever you are line-breeding is cheap insurance. Back when I kept more tanks, I was better on that. Now both the guppies and the shrimp at times drop down to a single tank each. But part of cutting back was the decision that if either of those crashed, I would just let them go.

The line-bred fish I keep are simpler. There are always indepenedent tanks of the rainbows. The Tanganyikan Cichilds are just particular favorites I enjoy keeping and breeding. They could be easily replaced or traded off for other species.

That is obviously the desired case, but is a major chore.

Since I only have the one species to worry about, and since RCS are so widespread, I've never really had much trouble; it's only twice a year, and it's easy to find good stock at a reasonable price.

I have a pair of mandarinfish I wish to breed (they spawn regurlarily). But they are brother and sister. Their parents are WC, so the inbreeding will be at only this generation. What do you all think about it? As their parents are WC, there will be some "fresh" genes from their parents. Should I worry about my mandarins being brother or sister? Or would that only be a problem if the inbreeding continues in later generations?

The WC have to be considered unrelated, so your pair are just F1, the first-generation inbred. Their offspring will be be F2, so may show some assortment of color, form, etc. characteristics. Variant characteristics and serious recessives do not show show up alive before F2, and even then must be selected for to be serious. The problems arise when some desirable trait is closely linked to a nearby undesirable recessive.

Brother-sister, mother-son, or father-daughter matings are routinely used to fix "desirable" variations or mutations which may be recessive. But as these can show up undesirable or fatal recessives, you have to watch the vigor of the line-bred critters.

I would not worry about F2 matings, after that I would want to out-cross if the aim is to hold the wild type. Out-crossing every second or third generation will hold most strains. If selecting for some specific non-dominant variant, you may have do F2 breeding to get the recessives traits back and F3 and F4 to stabilize it enough for practical breeding. That means that you pretty much have to keep out-crossing and re-selecting constantly. The lack of that extra work is responsible for the current sad state of livebearers and some amelanistic strains of fish (commonly called albino, which many are not).

Thanks! I don't personally have a problem with it, as the parents are WC, but I was thinking about when I sell the mandarins I raise (if I manage to raise any). I can breathe more easy now. I always want to do the right thing when I'm selling fish. That's why I always hate to sell fish (but I have to, of course, as I'm breedning cories). I feel responsibility for what I am selling, and you never know what will surface after you've sold the fish. Well, I don't have to worry about my mandarins being brother and sister then. But if I get as far as selling little ones, I will tell the buyer about the relationship.

Careful breeding is the only way to maintain high quality fish. The current state of the livebearers is a horrible lesson which many breeders ignore.

A friend of mine has guppies, and she had to stop breeding them - not because of population, but because she couldn't find good stock and hers were in such horrible, horrible shape, genetically speaking. Adding guppies from the pet store made no difference, and the really good ones online were astronomically expensive. She couldn't afford to keep her fish healthy and had to stop.

That is unfortunately not at all shocking. I have not seen decent guppies in ages. My LFS keeps the few guppies he does handle in the "special care/fragile and sensitive fish" section.

Neither of us has seen a real sailfin molly in decades.

don't forget to have fun folks !

Actually, I think genetic health IS kinda fun. It's a challenge - a pretty rewarding one, at that.

Without challenges, I would have left the hobby literally generations ago.

Yep... There's nothing like watching an animal that is too delicate to touch live and thrive in your care.