New Tank Trouble and fish deaths

Good evening all! I purchased a 36 gallon tank 4 weeks ago. Added substrate, a couple decorations, and plants. Then added water, Prime to remove chlorine, and bacteria starter. After allowing a heater to run for a day I purchased one harlequin rasbora. The fish lasted for three days, then died. I immediately removed the fish, waited three more days, and purchased three rasboras. All three died overnight the first night I had them.

My at home test indicated the water parameters were normal. I waited a few additional days and tested the water again. Parameters were as follows:
0 Ammonia
0 Nitrate
0 Nitrite
0 Chlorine
120 Alkalinity
7.5 pH
Water temp is 75

I added a three spot rasbora which seemed to do great for the first two days. So I added five mollys and a bristlenose pleco. Today the gourami appears very lethargic. It is hanging out near the top of the water in the center or in a corner, appears listless, and won't eat. The gourami is barely moving. The other fish appear fine. Is there something I can do to reduce the apparent stress on the gourami? I'm especially concerned because the other fish I added to the tank all quickly died! Thank you for any help.

 

It sounds like new tank syndrome. Did you cycle the tank further than adding the bacteria starter?

You'll want to do another test on the water. If it is as I suspect the ammonia will be above 0.25- you'll want to do enough water changes to get that as low as you can. Research fish-in cycling in the meantime.

In the future you may want to consider waiting longer than a few days to add in new fish. The sudden increase in ammonia can quickly overwhelm tanks even if they are cycled and cause them to crash.

 

I initially added some fish food without fish. Then thought the single rasbora in the tank would help the process along.

I just tested the ammonia level, which did not indicate any ammonia. I will start a water change of about 20% as that is the only thing I can think of.

I will wait longer before adding any additional fish.

 

I completed a 20% water change. This morning there is definitely improvement in the behavior of the gourami. She is moving around the tank and seems more active in general. Still not eating, but I will closely monitor that.
The Mollys and the bristlenose all seem to be doing fine. They are eating and moving around.
How often do you recommend completing these water changes for now? Thanks for the advice. I got bad advice at the pet store and I'm glad you could help me HOPEFULLY save these fish.

 

Too soon for fish.

 

???

 

I think what happened is that even though you have 0 on ammonia and nitrates, it increases when adding the fish and your good bacteria can’t keep up causing an overload of ammonia. I would say keep your current fish and do an in-cycle tank. Watch your ammonia daily and make sure your nitrates increase while your ammonia and nitrites decrease and eventually stay at 0. The good bacteria dies from starvation within a few days without any food and that could’ve been the cause during your “break” without fish in the tank.

 

I'd do 30% water changes every other day until your bacteria colony can handle the bioload. As others have suggested, your current bioload may have been too much for your bacteria colony to handle right now. Also, it's not the most important thing, but out of curiosity, what test kit are you using?

 

Well first of all, an update. The gourami is doing significantly better. I would say her behavior is normal and she is eating again. The mollies are really thriving as well. I will do another water change tomorrow. Very happy the fish appear less stressed.

The test kit is API 5 in 1 test strips. I have a separate ammonia test strip kit. What is your opinion of the test strips?

 

Well first of all, an update. The gourami is doing significantly better. I would say her behavior is normal and she is eating again. The mollies are really thriving as well. I will do another water change tomorrow. Very happy the fish appear less stressed.

The test kit is API 5 in 1 test strips. I have a separate ammonia test strip kit. What is your opinion of the test strips?

Not as accurate as a liquid test kit, but not the worst thing in the world.