the white usually means ammonia poisioning, so if your water is dirty with ammonia, do a 100% water change, but don't always do %100 water changes, it may mess with your filter (that's if you have one...)
I can't explain the clamped tail/fins but I see some parts of his tail/fins fading. I think he has fin rot, but don't worry. I'm in the middle of treating for fin rot, too!
I think you have to do a %100 water change and add a teaspoon of AQ salt, premixed. (Aq salt is Aquarium salt) keep it up for a few days and fin rot eventually fade away, his fins and tail will grow back soon, if it is fin rot.
/I]But I'm not %100 sure so don't do it unless some more advanced people come on this thread and reply to you. [/u][/b]
Fin melt is a form of fin rot. And apt to its name it appears as if the fin was melted together like when you melt plastic. IT doesn't look like the above pic is melt and actually white/clear means REGROWTH, not rot. The tiny black dots on his tail could be the beginnings though. Treat with aq salt after performing a 100% change. Make sure it's aquarium salt (ordinary salt is harmful, like table salt and sea salt) 1 tsp per gallon for a maximum of 10 days.
Make sure he is eating and pooping and swimming fine otherwise. With clean water, the fish will follow (as one member here puts it wisely)
Fin rot is caused by excessively bad water over time. Keep it clean :)
He looks fine to me. I think the clear sections are his fin growing back and the curl may be due to hard water. Is he new? he may of had slight fin rot and now its healing
THIS is fin melt - from a past thread on here.
The fins literally look like they are melted together
100%'s once a week are highly recommended for non filtered tanks..or when treating illnesses but not for cycled tanks. Although I do it on my storage bin. It sits on the floor so a siphon won't work, which kinda sucks since the inhabitants are poop machines