megsmelody said:
I use a liquid kit, but it only indicates ammonia. I set up the tank maybe 2 months ago. I let it run without fish for a week. Is that enough of a cycle?
How can I do fishless cycling I'd not everyone is dead yet?
Unfortunately, letting the tank run empty for a week is the pet store version of "cycling"...but in reality it does nothing. Actual cycling is developing beneficial bacteria in your filter which will convert the toxins your fish produce and keep the aquarium safe. Letting it run empty without an ammonia source really does nothing other than circulate the water...I'll never understand where that recommendation comes from
It's hard to know exactly whats happening without full test results...but I'd take a guess and say you're in the nitrIte spike phase of your cycle. This is an extremely dangerous time for fish...and you have to perform massive amounts of water changes to keep the toxin levels down. Are you currently doing water changes? If not, they need to be done every day...I'd start with doing a 75% change ASAP (using the Prime), then move to at least a 50% water change every day.
As Brittany said, the majority of your beneficial bacteria is in your filter media. Replacing it is a disaster waiting to happen. Make sure you keep it until it is literally falling apart, and simply swish it around in tank or dechlorinated water to remove the debris it builds up.
Now here's the other issue...stocking. Normally I just provide a link which shows you how to keep your fish safe during a fish-in cycle...but unfortunately in your case there's more issues than that. Both Tetra species you have need to be in a school of at least 5-6 members. That alone would overstocked your tank. I also feel 10 gallons is too small for a Dwarf Gourami...and even though Otos are small, they should ideally be in at least a 20-30 gallon, well established tank.
Telling people to return / rehome their fish is one of the last things I try and do...but unfortunately I just don't see a way for it to work with what you have. A 10 gallon really doesn't provide many options for fish...the smaller a tank is, the more difficult it is to maintain good water conditions as well.
Sadly a 10 gallon simply isn't enough water to provide the fish you have with a suitable environment IMO. Do you have any friends with established tanks you might be able to donate them to? Is it a possibility to upgrade to a larger tank like a 20 long?
Here's a few links to read. The first step right now should be large, daily water changes using Prime. Also do as much research as you can on the nitrogen cycle in aquariums...and potentially see if finding new homes for your fish is a possibility.
http://www.aquariumadvice.com/artic...g-but-I-already-have-fish-What-now/Page2.html
http://www.americanaquariumproducts.com/Nitrogen_Cycle.html
http://www.aquariumadvice.com/forum...guide-and-faq-to-fishless-cycling-148283.html