Guppy breeding and selection guidelines needed please.

My daughter started breeding Koi Guppies about two years back. They were obtained from and import and she is really doing well with them .

Over time she has managed to get males with bigger and bigger tails and soon we were seeing many different tail variations and it was slowly moving away from the original round tail. Many local breeders want to buy males from her as they are interested in the bigger almost triangular tails.

My question then, is it okay to breed a strain that does not look like the original fish they came from or should I discard the bigger tails and only keep the rounded tail males and continue to breed with them to keep the original appearance intact. We have reselected breeding stock a week or two ago and i have allowed for tanks with 3 males and 10 females per breeding tank. I am inexperienced and don't know what to select. Where can i find literature or guidelines on continuously selecting the best specimens for future breeding.

Her Koi Guppies looks like these:



Then we received the following strains yesterday. 2 from local breeders and a full bag from an import that landed yesterday.

Turquoise Bluetail guppies (Local)


Read Tail Dumbo Ear Guppies (Local)


Green King Cobra Guppies (Import)

 

Selective breeding is how we ended up with so many different variants, It's the foundation of breeding.

If you find a trait that you like selective breeding is the way to go. None of the Neocardia shrimp that we have today are natural occurring, they only exist through millions of cycles of selective breeding.

You will always find purist that do not approve but you will find that in all hobbies. I know someone that breeds Clivias and he hates hybrids.