Ok, so from all of that, I think this is what you are left with right now?
2 Zebra Danios
11 Neon Tetra
4 more Zebra Danios
I agree with everyone that it is overstocked... sometimes set ups like this will work but in the long run, having this many fish will probably shorten your fish's lifespan dramatically. I have a 10gallon/40litre tank with 8 fish and thats pushing it and your 50litre is only slightly bigger. My suggestion for your fish is if you don't want to get rid of any, is there a possibility of buying a second 50litre tank? You could split your danios and your neons in half and put like 8 in one tank and 9 in the other. Or, any chance of maybe upgrading your tank altogether and getting say a 100litre that all of them will fit comfortably in? Craigslist.com is an excellent place to look for used tanks for cheap prices. I know sometimes upgrading isnt possible though, so in that case, I agree with everyone else to keep doing daily water changes until you get your test levels back to normal. Then I would also suggest doing a 30% water change twice a week after that. For small fish like you have, they dont eat much (a whole lot less than most people think). Try and give them only enough food that they will consume in about 3 minutes. Good luck!
2 Zebra Danios
11 Neon Tetra
4 more Zebra Danios
I agree with everyone that it is overstocked... sometimes set ups like this will work but in the long run, having this many fish will probably shorten your fish's lifespan dramatically. I have a 10gallon/40litre tank with 8 fish and thats pushing it and your 50litre is only slightly bigger. My suggestion for your fish is if you don't want to get rid of any, is there a possibility of buying a second 50litre tank? You could split your danios and your neons in half and put like 8 in one tank and 9 in the other. Or, any chance of maybe upgrading your tank altogether and getting say a 100litre that all of them will fit comfortably in? Craigslist.com is an excellent place to look for used tanks for cheap prices. I know sometimes upgrading isnt possible though, so in that case, I agree with everyone else to keep doing daily water changes until you get your test levels back to normal. Then I would also suggest doing a 30% water change twice a week after that. For small fish like you have, they dont eat much (a whole lot less than most people think). Try and give them only enough food that they will consume in about 3 minutes. Good luck!
