It appears a bad gene or exposure to some kind of chemical messed with frogs development. Don't think a bacterial infection would deform the tail, so will rule that out. If kidneys, lymph hearts or liver suffered developmental problems, it could explain deaths and bloating. If such is the case, there is not much to do and help. Bloating is sometimes relieved by an Epsom Salts bath solution (rate of 1 teaspoon per gallon of dechlorinated 80F water) to frogs chin depth. Good luck

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