RE: guppy problems
It is very true that inbreeding reduces a fishes immune response and results in defects, namely cuved spine. I believe your problem was either fungal (from dirty water, usually saporgelia) or flexibacter columnaris (bacterial, very leathal, has nothing to do with dirty water) The way to tell the diffrence is, fllxibacterium eat at the fishes skin itself, and resluts in brownish dead areas, while fungus mainly attacks the fins and grows on the skin but does not eat it.
Treatment for this is One of 4 gram negative antibiotics that are the most powerful, Terramycin (oxytetracycline) Maracyn 2 (minocycline) or Kanamacyin, tho triple sulfa antibiotic should work as well. Fungus often goes hand in hand with flexibacterium infections, so you can combiine a anti-fungal product like methylene blue or primafix or Furan with your antibiotics. Fugus itself is also leathal, and is the result of poor water quality. Flexibacterium do not present itself in a "dirty" tank, it is opportunistic aerobic (breathes air) bacterium that is very contaigious. I reccomend giving the kanamycin/nitrofurazone or Minocycline/primafix or Triple sulfa or Terramycin/methylene blue a try in the future (like if you see alot of fry clamped and dying) They are hard to tell apart, and have completely diffrent treatments, raise temperature to kill fungus and lower temperature to slow flexibacterium. A good amount of salt will help a great deal, 2TBSP per 5 gallons during treatment. (1x)
Inbreeding guppies can only go well for a few generations (about 1 year) before you must aquire new bloodline. Guppy farms start with "Breeder seed fish" and colony breed them for a couple generations, then they mix them together and get lots of diffrent colors, then after that they throw them into a pond where they all breed together and become wild lookin and then they are sold as "feeder" guppies that resemble the wild guppy (have some) Any good fish breeding program will need new blood. It can be of the same variety but from a diffrent source, as in fancy goldfish, or it can be by combining two or three diffrent varieties to get a pretty hybrid, but eventually, fish that constanly inbreed will die.
