Flower, this is the first time she has ever come down with any disease that I have observed. Since EGBD is more of a "symptom," than an actual disease, it's not very likely that she caught it, so to speak, from any of Theresa's horses. EGBD is thought to be brought on by bacterial infections or supersaturation of CO2. I read a blurb as well that links EGBD with water quality issues as well.....and this is the line of reasoning I'm most interested in. Consider this:
It's no secret that this girl has been by herself for over a year now in this tank. She had a few finned friends come and go, but as far as actual seahorses...well, she's been all alone. The tank's parameters have been stable at 0-0-0 for the big three for quite some time. My idea of a nitrate spike was when I went up into the 10s. Now, I go and add a total of THREE new horses to the mix. I firmly believe the simple addition of new life in your tank is going to cause at least a little stress to the original occupants....imagine living in a single large room for a year, then all of a sudden having three guests show up and start claiming bunks. I know I'm anthropomorphising the horses, but I can't help but feel that the analogy is similar. So, you have a certain amount of low-level stress on the animal due to more crowded conditions.
Now add to that the inevitable deterioration of day-to-day water quality. This girl was used to breathing pretty clean air here....so to speak. Now (due to the increased bioload,) I ALWAYS have nitrates. A good day for me is in 10s, but as I'm writing this right now, I'm in the 20s. I'm working to bring that number back down, but you get the idea. I'm sure that, for an animal that was so used to a specific water condition, the lower overall quality is also a stressor that contributed.
Finally, let's talk about the poor husbandry that week. I'm to blame for this. I let the tank go for some time without really checking on it. If I had really looked, I would have seen that starfish earlier. As it was, I basically removed a DEAD, ROTTING carcass from the tank. I'll bet there was a brief ammonia spike, and you can be sure that my nitrates were astronomical that week.
With all these problems in the tank, it wouldn't surprise me if her immune system was weakened a little...possibly enough for a bacterial infection, possibly the EGBD was caused by some other reason. But if you again apply human terms to the problem, consider how easy it is for us to catch a cold when we're tired and stressed. When our immune system crashes, it's often just a matter of time before some bug latches on, and I wouldn't be surprised if the process was similar in animals. It goes without saying that I'll be watching her like a hawk for the coming weeks and months to make sure that the GBD does not come back. I'm very much hoping that this was a symptom of some seahorse equivalent to the common cold. As of this very moment, she's looking good, her tail is the right size, and she's actively looking for food. Now I can go take a nap (mainly because I caught a cold this weekend while out fishing in the rain!).