100% agreement with the other posters. I know you have other geckos, so just don't take the risk. Looks to me like the top one might theoretically be savable (still has some fat in the tail), but it's just not worth the risk to your other animals (or your emotions if it doesn't work out). Trust me on this, I've lost one that started out looking much healthier than that due to parasites, but the gecko in question first looked normal, then like the top one, then like the small one. By the time he looked like the second one, he was almost completely unresponsive. The end was when I picked him up to hand feed him and he didn't even react/notice. Then had to make the decision to take him to the vet for euthanasia. I'm normally one of the more emotionally controlled people you could meet, but I cried that morning, because I'd tried so hard to save the little guy (vet trip for antibiotics, hand feeding him every night, etc...) that I'd become even more attached to him than before, and before he got visibly sick, he'd had such an amazing personality that I was already very attached to the little guy. It was one of the most difficult and emotionally draining experiences I've ever been through, and one I wouldn't wish on most of my enemies. It still makes me sad to think about it, but a picture of him watches over my other lizards from a place of honor up on the wall.
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0.1 Albino Leopard Gecko - Tigger
0.1 Crested Gecko - Pooh-Bear