Hello guys, I am hoping someone can help me figure out why I am losing my neon tetras.

I have a 36 gallon tank, we got the tank on the 19th of February.
We added water, fish fakes, and stress coat tank starter stuff.

The pet store recommended not adding fish for 3 days, we waited 4. We added 4 neon tetras, 4 cherry barbs.

We lost 1 neon this weekend, and another when we got home from work tonight.

I have an API Freshwater master test kit, have been testing water regularly.

Our pH level started out at about 7.4, but over the course of 3 weeks has been rising .. now up to about 8.3 even with small 25% water changes once a week.

Our Ammonia levels are measuring about .25ppm, one reading before last water change was up higher at about .4ppm

Nitrites are staying low .. 0 to .25ppm

Nitrates have been 5-10ppm

Temperature is about 71 F


We did add "Bob the Janitor" last week .. a pleco ... the one spike in ammonia was likely due to him not cleaning up the algae tab.

2 Neon's have had funerals, and will be missed.

We have 2 plants, 1 giant hairgrass, 1 microsword.

Any advice is appreciated.

Waiting 3 days before adding fish to your tank was bad advice. It takes much longer than that to cycle a tank. So, you started off doing a fishless cycle: adding fish flakes to the tank to create ammonia in order to build a colony of beneficial bacteria to make the water safe for your fish. But you added fish way too soon, so at that point you were cycling with fish in the tank. Many people cycle their tank using fish, but neon tetra are a very poor choice to do this with. They are too sensitive and require a fully established tank. Bob the Janitor was a very poor choice as well, because of how much waste plecos produce (it was probably his poo that created the ammonia spike, the algae has nothing to do with it). Your ammonia levels are still to high. They should be zero. Don't add anymore fish until you get that down. Returning the pleco would probably help. If it's a common pleco it's going to outgrow your tank anyways. Hopefully with a little experience you can choose a new handle! Best of luck.

The fish got ich because their immune system was compromised by the ammonia and nitrite. Ich is a fairly common pathogen that can be present for a long time but only gets the best of fish when they're already weakened by something else. They will probably be able to rid themselves of ich once the water is clean. It might be a good idea to put the filter back on and do a 1/3 to 1/2 water change with dechlorinated water every day until ammonia and nitrite stay at 0 ppm. Then do a water change every time the nitrate rises above 40 ppm.

From the time the first fish flakes are added to the time you're done will take about 40 days. There is a graph on slide 8 of this presentation: http://www.ag.auburn.edu/~davisda/class ... Design.pdf
You need the filter on the tank because that's where the majority of the beneficial bacteria live. Without them, the tank will continue to present a high ammonia and nitrite concentration. I hope you kept the sponge wet after you unhooked everything, because if it has dried out then you might have lost the three weeks of beneficial bacterial growth you had been culturing. sorry :(

Here is some more information: http://www.fishkeeping.co.uk/articles_5 ... rticle.htm