All My Fish Are Dying!!!!!

[S._Hispidus]

I recently tested my water, like yesterday. I have lost four fish in three days. The Ammonia is 0, the Nitrite is 0, but the nitrate is around 40. How do I get this to drop? do I need to do water changes? I don't currently do those.

[MonoSebaelover]

We need a lot more information to help you. What fish are dying? What size tank is it? What other fish are in the tank? How long has the tank been going? Answer these before we help you with why your fish are dying and whether inverts are good for your tank (cleaning crew).

[OrionGirl]

Agree with the above, but I want to confirm--you're saying you've never done a water change? How long has the tank been setup? Do you do FW topoffs?

[kreblak]

Nitrates at 40 should not be killing fish. However, we're missing a lot of your water parameters here. What is your water's specific gravity? What is your PH? What temperature is the tank water?

If you have never done a water change, you could be having a system PH crash. Seawater acts as a buffer, and as fish excrete wastes, they also excrete acids into the water. Some acid is also the by product of bacteria respiration. Seawater is able to buffer these acids, but not indefinitely. Seawater titrates over a period of time, and eventually loses it ability to buffer acids, resulting in the steady lowering of its PH. Water changes add fresh saltwater to the tank, increasing the buffering capacity. SW fish need a PH of 8.0 to 8.4, so that is a possibility for your tank. However, we cannot say for sure without your other water parameters.

Do you possibly have a disease that is killing your fish? Look for signs of Ich, Velvet, or fungus.