I am getting my new tank tomorrow, which is much, much sooner than I had orginally thought.

Right now I have six fish in a 30 gallon tank (way overstocked I know, but these fish were given to me in this situation). I am looking at either a 55 gallon tank, 90 gallon tank or a 100 gallon tank, that is all the store has in stock right now.

Which size tank is best for my fish?

What type of filtration do I need?

Should I run the tank without the fish? Should I add a fish for the cycling?

If I should add a fish, should it be one from my tank now (these fish have already been through a lot in the past few weeks), or should I buy another one to start the cycle?

Should I just move all my fish from the 30 gallon into the new tank? The ammonia and nitrite levels are getting much harder for me to control now.

Any advice would be greatly appreciated!

Hello Ferrah! Well first off, what types of fish do you have, and how big are they? It would help to know that before saying what size tank you would need and what type filtration. IMO the new tank should be set up and cycled before adding any fish. Do you have two filters running on the existing tank? You could put one of those on the new setup to aid with the cycling process.

I know that there are alot of other folks on the forum that could help you much better than I can, but I will do my best to help in any way I can. I am still learning too. But you have come to the right place- lots of great people who are quite knowledgeable.

Good luck! And

I have two orandas that are nearly two inches. Two fantails nearly two inches. A 1 1/2 inch black moor. And a 3" oranda. I rescued these fish, and the guy said he had the big oranda for nearly six months and the other fish for about three months. These fish came all with their own equipment, so I didn't need to buy hardly anything.

I am having troubles lately controlling the ammonia and nitrite levels. I don't know if this is because the tank isn't properly cycled (I didn't clean any of the filter media when I got the tank), or if it is just because the tank is really overstocked. I check the ammonia and nitrite levels daily and I almost always end up doing a 20 to 40 % water change. I do nearly 100% on weekends. Things are getting worse, not better as far as upkeep goes.

The fish have been through quite a lot lately. The fish were not fed properly when I got them. (they were fed when the guy "felt like it"), they have had to move with this guy twice in the last month, and then finally to my place their new permanent home.

I have two filters running on this tank, but one of them I bought myself for more filtration.

I am worried that moving them yet again to another tank will stress them out too much. But I am also worried that if I leave them in their current tank for too long, that they will succumb. I'm really not sure what to do!

Get the biggest tank you have room for and can afford. The more water you have the easier it'll be to control the parameters. Maybe not at first since you'll have to establish a cycle, but hopefully using your old filter media will do it pretty quickly. Then make sure that all your filtration (added together) is at least 10x tank volume.

The parameter problems you're having sounds like a combination of overstocking and not having a well-established enough cycle to deal with it. Just keep doing as many water changes as possible to keep the numbers down and your fish should be fine once you can move them to their new home.

If you are showing nitrites and ammonia, then the tank is not cycled, the overstocking isn't helping... but at this point the ammonia and nitrites are causing more stress than would be caused by overstocking.

Since your tank is not cycled, I would suggest getting the largest tank you can, and moving the fish right into it dealing with cycling on a larger tank will be less stressful for them than dealing with it in an overstocked tank.

Filtration like Nenn said being 10x the capacity of your tank... that is to say, the combined pumping power (in gallons per hour) of your filters should be 10 times the size of your tank... 55 gallon tank, 550 gallons per hour pumping power.

If you go with the 55 gallon tank, you will still be overstocked, but you can keep two or three of your fish in the 30 gallon along with proper filtration, and then put the rest in the big tank, and that'll provide them all with enough space and filtration.

I would not get any more fish at this point. No matter what happens, the ones you have are going to have to deal with finishing off the cycle of your tank... be it in the larger one or the smaller one.

Also, if you were to get another fish, for the health of all your fish, it should be quarantined for about a month before being introduced to the other fish... and that is just more complications that you don't need.

Though, I'm still a newbie in this department, so keep that in mind. :)