They want to play with each other or they are bored and hungry. The third reason is bullying, leave the fish that bully's in a seprate tank for a while until it stops.
Some fish (for example guppies) have long wavy fins, some other fish such as mollys like to nip at these fins, if your fish are doing this then it would probably be best to buy another tank and separate them.
Scoop all your fishes to another tank or tub of water and clean the fish tank just as you would normally without the fish
Aquarium is another name for a fish tank
Aquarium is another name for a fish tank
You don't buy the fish. Unless, of course, you have another tank that is ready.
the fish tank
Not unless you had another fish in there.
A betta fish? You can't or they will kill the tank partner
fish tank
If you are going from the pet-store's tank to yours you should place the whole bag into your tank for at least 30 minutes then release the fish. If you are going from your tank to another tank you should wait until the tanks are the same temperature then go from one tank to another.
A fish tank would be considered an ecosyestem because there is a living thing in it. (the fish)
Yes but you would have to clean/scrub the tank out properly first.