I've noticed some odd behaviour in my neons lately. Every once in a while, they'll start swimming around with their heads pointed slightly downward. It happens randomly, for not apparent reason, but then is gone again the next day. And they all do it at the same time. Its happened a couple of times after feedings and water changes, so I'm wondering if its a reaction to stress, and perhaps to overfeeding? I've tried to be very careful about feeding, giving no more than they eat in a couple of minutes. But mebbe I should cut back further? Suggestions appreciated.