It May have loved long, but not well...
remove the divider and allow him the whole tank. Of course, only with him in it. Next time, opt for a one gallon bowl at least per fish. They're the same price.
also, you're going to want a heater, 76-82' is needed. Look for something under or at 10w. Its hard to heat such small tanks. Get a thermometer, too, to ensure the temp isn't too high.
I know we're on you about this, but you seem to care and the fish are so nice, you'll want to keep them their happiest and healthiest!