Tank is a new 40 gallon. I'm running an aqua clear 50. I had 2 neons in the tank when I added the Romney and 4 other tetras. Rumney lasted 2 days, also down two neons as of this morning. My ph is 7.6, temp 76 nitrates and nitrites appear to be 0. I have two pieces of mopani wood, 2 ceramic caves, 3 live plants, 7 fabric plants and a gravel substrate. Water was added 3 weeks ago, after 48 hours I added 4 neons. Have not cleaned gravel yet, nothing to really clean. Have only replaced 6 gallons. Water was tested at fish store and was told it was high, they sold me something to bring pH down, each time I did it I lost a neon, so I stopped doing it. Well water has a high ph. Was not using pH balancer when new fish added. The 4 tetra I have now are active, but nippy with each other. Not sure what to do at this point.