Thank you.

fish waste is ammonia (humans produce it too- its what makes pee smell). In a cycled tank good bacteria in your filter turn this into nitrite. Other bacteria turn this into nitrate. Ammonia and nitrite are toxic to fish, nitrate is less so in low levels. Some fish are more sensitive to ammonia and nitrite than others, osacars dont do well in ammonia and nitrite

When starting a new tank it takes a while for the bacteria to grow in your filter to turn ammonia into nitrite into nitrate. Thus is call cycling. So you need to get your filter running nicely with a good load of bacteria to turn the ammonia into nitrite then into nitrate and to do this you need a source of ammonia. You can either add something like stress zyme or you can put fish in that are not sensitive to ammonia and nitrite, like danios for example. You then test your water and once ammonia and nitrite are zero you can add oscars. However you will then be left with deciding what to do with the danios or they will eventually become food for you oscar

You reduce nitrate by doing water changes

An alternative way to cycle a tank is to get some filter media (the little rocks or hollow tubes) from another filter that is cycled and put it in your filter at the same time as adding your oscars, if you get enough media your tank will be almost instantly cycled

Yeah I was going to ask. I have 30 gallon community tank (with a 75 gallon bio filter). The bio filter on my community tank uses to media... I will call them packs? If I take one of the media packs and put it in my new filter will it speed up the cycle?

Yes definitely. But you have to transfer the packs at the same time as you add the new fish. If you put the pack in the new filter without any fish (ammonia source) the bacteria will start to die off. Also dont forget to put a new pack in to replace the old one.

Keep testing both tanks for ammonia and nitrite and nitrate. The old one to make sure the rest of the filter takes up the slack and the new tank to see how well it is cycling

Thank you, I am going to try that out. And keep up with the testing on both tanks.

Hello! I just set up my tank and am ready to start cycling it. I have a community 45 gal. tank and know how to cycle it, I was just wondering if you can cycle a tank with oscars or if you need to start with other fish first. Thanks!