Flashing Loach

[Southerrrngirrl]

I noticed last night that one of my Zebra Loaches was flashing quite a bit on the gravel, and this morning it is still doing it. I'm really concerned. I've seen fish flash before but never like this, its pretty constant. He otherwise seems fine, looks normal. I can't see any obvious signs of disease or injury. He's the only one doing it in the tank.

Tested water - nil ammonia, less than 5ppm nitrate, nil nitrite, pH is high, probably around 7.2-6, which is fairly normal for my tank though. It's not high enough to register on the High pH test. I did a water change and gravel vac on wednesday night. The only changes I've made to the tank is that I added new plants and an airstone yesterday along with 3 small albino corys.

What should I do?

Edit: Just noticed my other loach, when he's resting on the gravel he's got his top fin clamped, when he's swimming its not clamped. He's not flashing though.

Oh man, I really do not want to lose these little guys..