I bought a 14 gallon tank and i put the salt water in and some other liquids that they told me to put in and the store I got the tank from told me I could put a few yellowtails in there straight away but that I would have to wait about 4 weeks to get the more expensive fish. Anyways, so I got 2 yellowtails and one little fish which was black and white striped (i dont know the name), and s after 3 weeks, the black and white fish was just laying on the bottom, it wasn't dead but it seemed to be breathing fast and it was just still on the bottom, and I don't know what's wrong with it? what do I do, does anyone know what it has? And will this affect on the time that I have to wait for the tank to be ready for the clown fish that I was supposed to get after 4 weeks?