Det blir nog inga humlafiskar ändå. Det är inte värt att riskera hanarnas fenor.
Du råkar inte veta mer om guppys naturliga biotop? Stenform, bottenmaterial, växter, vattenrörelse osv?
Så här står det på
http://guppyplace.tripod.com om salt:
"Salt is an excellent and safe-guppy remedy for various problems when avoiding chemicals, and a good general additive to relieve stress and protect against ich. It also prevents nitrite poisoning (brown blood disease) in fish. However, salt in guppy tanks is not mandatory and is not advisable if you have a community tank with anything other than other salt-hardy fish.
When adding salt as a regular additive to the tank, top up the tank before/between water changes with unsalted water. The reason for this is that salt does not evaporate and eventually a build-up of salt will accumulate in tanks that are not regularly topped up with plain water. Then, add the ratio of salt to the water you have physically removed from the tank. For instance, if you have removed 5 gallons and the tank is kept at 1 tablespoon per 5 gallons, dissolve one tablespoon of salt in the water before adding to the tank.
It is a myth that table salt is toxic to fish. The iodide can be helpful and the anti-clumping agents are minute and fish-safe, though it sometimes clouds the water slightly. However, avoid salt that contains such items as dextrose.
Other safe alternatives to expensive aquarium salt include sea salt, pickling (cooking) salt, and solar salt. Salt, when added to guppy tanks, is usually in the amount of 1 tablespoon per 5 gallons, or 1 teaspoon per gallon."
