Hi all, I'm seen that with new fish, even when it is "gourmet fare" like a mosquito larvae or Blackworm.
I give my fish a lot of live food, so they usually pretty quickly cotton on to "things that wriggle".
The funniest to watch were the Marbled Hatchets, they used to get really excited when I changed the water, because they knew there were likely to be
Daphnia, Cyclops, Asellus etc in the water change water (I use rain-water). I use old 6 pint milk cartons for the water change water and I change about 10% a day (two cartons worth on a 60cm tank).
I bring the water into the house over-night, but in the winter often it would only be ~15oC when I was tipping it into the tank, which would be at 25- 27oC. You could often actually see the thermal stream of cool sinking water.
According to a lot of things you read there would be <"
thermal shock issues"> if the fish swam into the stream of cold water, but that didn't bother the Hatchets, they would fight with one another to be right under the container and to have first go at any crustaceans pouring out. They also used to quite often leap out of water as well, so you had to keep an eye on them to make sure that they hadn't escaped from the tank.
Immediately after water change it would be back to hanging stationery, just below the surface, in the <"
stream of water from the filter">, each fish positioned as far away as possible from the others, while still being in the (admittedly gentle) flow.
cheers Darrel