I'm glad you PM'd Sakura. Hopefully, she'll know what's going on....
Some questions which occurred to me as I read through the thread:
1) Did Moose (or his equipment) have any contact with the new girls? He looked great the other day, and this had a very sudden onset. Is it possible that he was somehow exposed to a disease from them? If they were exposed to it early on in life, their immune systems may have developed antibodies to it. But if Moose hadn't been exposed previously, it may be something that could affect him.
2) You said you've had other males with similar symptoms die in the last few weeks.... Is it just males? Were they all Giants? And is there any chance there was cross-contamination via water or equipment from their tanks? Did they die in quick succession? What was the lag time (time intervals) when each developed symptoms? Did they get sick at the same time? Or did each occur several days apart, etc? Can you determine any type of timing pattern?
3) From what I'm reading, it sounds like he was OK until Tues 8/20. Then he suddenly developed a gray belly, lethargy, and lay on his side on the bottom. (In the photo, it also looks like there could be slight bloating.) I don't know anything about Giants or their anatomy, but could they be prone to some kind of food/feeding issues? (I'm not thinking this is the cause really, but I'll ask about it, just in case.)
4) The Thurs 8/22 photos were WAY better than those from the previous day. So, at that time, the Kanaplex/Epsom salt (2 tsp/gal) definitely seemed to be helping.
5) You said that today, the gray streaks on his back/belly turned black. Was he lying on that side? If so, could it the pressure from lying down caused bruising? (Marine mammals who are beached will develop dark regions where their bodies are lying on the sand. If they stay beached for long, it starts to cause internal damage, due to their massive weight. A betta probably wouldn't have this sort of damage, but I wonder if there could still be bruising since they don't normally lie on their sides.)
6) How is his behavior today? In today's photo, it looks like his color is much better than it was the other day - is this the case?
7) So he's on the 2nd round of Kanaplex right now? And you're still using 2 tsp/gal Epsom salt? When was the last time he pooped? Was it normal-looking?
Mmmpphhfff.... I'm out of questions.... and ideas.... Kanaplex and Epsom salt still sound like the way to go, though. Kanaplex is one of the few antibiotics that can treat both external and internal issues. And the Epsom salt should help, as well. But I'm concerned because if you've had other fish with similar symptoms, then it could be something contagious, and it seems to have a very sudden onset.
I'll keeping thinking about this. Hopefully, Sakura will have something definitive....
Last edited by LittleBlueFishlets; 08-23-2013 at 05:40 PM.