The frogs are usually only found in the wild in Ecuador.
Dozens of highly toxic rare poison dart frogs have been bred in Hampshire.
The tiny baby phantasmal poison frogs, measure less than 1cm (0.4in) in length but have a poison 200 times more powerful than morphine.
They are only found in the wild on the western slopes of the Andes in Ecuador, South America, but have now been bred at the Blue Reef Aquarium, Portsmouth.
The baby Epipedobates tricolor frogs are red with three green fluorescent stripes. The species is endangered.
The colour of the species can vary from dark brown to bright red, depending on origin and inbreeding, and their stripes can be cream-colored, yellow or green and run from the head to the rump.
The frogs' poison can block pain 200 times more effectively than morphine
Jenna MacFarlane, from the Blue Reef Aquarium, said: "Virtually every species of poison frog is threatened in the wild. Among the biggest threats are loss of habitat and pollution.
"To be able to breed this particular species successfully in captivity is extremely rewarding.
"We have done our utmost to replicate the conditions they would normally experience in the wild and the success of the breeding programme would seem to indicate we have managed to get things just about perfect."
The International Union for Conservation of Nature considers the phantasmal poison frog to be endangered, which means that it faces a very high risk of extinction in the wild.
The species is now thought to survive in only seven sites on mountains in the Boliar Province in central Ecuador.
The aquarium said that it was hoped the phantasmal poison frog could one day help save lives.
Scientists have discovered that an extract from the skin of the phantasmal poison frog Epipedobates tricolor, a chemical called Epibatidine, could block pain 200 times more effectively than morphine, and without addiction and other serious side effects.
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