What do you mean by "weird"?
It means the tank should be cleaned.
Salt Water Fish
Assuming the dirty fish tank has had fish and water in it, without doing various specialised water tests it is impossible to tell what is in it.
It might be unsafe to drink because fish food, fish scales, fish waste, and many different kinds of bacteria are in fish tank water.
Live Aquaria provides you with supplies to preserve a fish tank with salt water fish. Fish tank provides lighting, fish food, and more to help you maintain your salt water fish tank.
14
The white scale on the inside of the fish tank is from a buildup of minerals that were in the water.
Robert Frost
Scoop all your fishes to another tank or tub of water and clean the fish tank just as you would normally without the fish
look on the internet
the cause might be a sick fish, a dirty tank, or over feeding.
put the live fish in a bag filled with water and change the tank then put the fish back in.