platy with puffed out scales

Question
Our little orange platy has been very healthy until tonight when I noticed his scales are puffed out.  He is still lively and seems to be eating, but that can't be good-he is also lighter in color-what could be causing this?  It is a 10 gallon freshwater tank with 3 tetras and 1 zebra fish, and everyone else seems fine.  The light in the tank hood malfunctioned recently, but as the tank is in a sunny window I thought it would be fine, but maybe not.

Answer
Hi Jennifer;

Poor little guy. His condition is known as dropsy. Fluid is building up in his body for some reason. Here is a web page about it with treatment options;

http://badmanstropicalfish.com/articles/article24.html

At Your Service;
Chris Robbins