See the vet and fast
It depends on if you are doing a complete water change or a partial water change. I usually just leave the fish in and siphon off about half of the water than replace the water. The fish get a bit nervous but seem to be fine with being left in the tank. To answer your question: No, you do not have to remove the fish when changing the water.
When you are changing the water in a fish bowl, you have to empty cup ot bowl with water in it. Then, put it into clean water.
Fish vomit from changing water conditions or from eating something bad.
plankton
they eat fish because of there water holes it is all there is to eat
Salt water fish eat fish that are smaller than them then those fish eat zoo plankton then zooplankton eat phytoplankton. I have appreciated answering these questions so if you have anymore go to askanything.com Also, it really depends on the fish.
Fishing spiders live in the ponds and will eat fish depending on its size. If you feed a fish to a tarantula, it will eat it. Tarantulas eat fish, but they do not live near water.
Eat the fish
water
Rats will eat almost anything. If the fish were close to the edge or the pond wasn't deep, it would be possible.
they eat little fish
they will eat any small creatures. This includes fish, mice, frogs and water snakes.