Cursed fish tank?

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Hello! Maybe someone on here can shed some light on this mystery.. I'm actually posting this for my brother-in-law, as I'm usually his go-to for tank help, but I am at a complete and utter loss.

As the title implies, I'm pretty sure my b-i-l has a cursed fish tank.

Currently he has a standard 55gal tank, basic run of the mill lighting, 2 power filters (both rated for 55+gal. One actually has media; sponge, carbon and zeolite. The other only fluff.), the substrate is a mix of sand, gravel and river stones, he has a few live plants as well as fake ones and some fake drift wood/rock looking stuff. The live stock in the tank consists of 2 black skirt tetras, a few cory cats, 5 neon tetras and 1 painted sword tail. The last time I checked his water it was 74F, pH was 7.2-7.4, ammonia was 0, nitrites was 0, and nitrates bounce between 0-10 depending on how close he is to water change day.

He recently tore down the tank and started all over (the sand bed, decor, and plants are new. Its used to have blue/white gravel and funky decor that looked terrible) because he was losing fish left and right. I checked his water each week for him and it seemed no matter what he tried he could not get his ammonia down. Eventually he took the only survivors and gave them to a friend, and tore the tank down. After a little work, he had it back up and running. He left the tank fish-less, with only a few live plants, for about a month and a half. Finally we tested his water out and everything seemed pretty ready for 2-3 fish (2 black mollies, and a red platy).

The fish lasted a week and died. He said it looked like they head "heart attacks", started to freak out and then just bellied up on him. So he left the tank fish-less for another week, did a 25% change, and tried 3 more fish (this time the painted sword and 2 neon tetras). I checked his water a few times and everything seemed to stay pretty stable, but within 2 weeks the neons had done the "heart attack" thing and died. So he waited a few days and brought home a neon blue dwarf gourami and was given the black skirts, neons and cories from a friend. All was going great for about 2 weeks and he ended up loosing the dwarf gourami out of the blue. This time around though he noticed that the tank smelled "moldy" and there was brown moldy looking stuff on the underside of the hood and the back of the tank. I had never heard of brown mold, but brown algae and did a quick look up.

I read that brown algae is pretty common is newer tanks where water chemistry is off, theres not enough oxygen, too much light, etc. So I told him to try and clean his hood as best he can, scrape the algae off the glass, and do a pretty big water change to try and clear it out. I also had him pick up a bubbler to try and put more oxygen in the tank. I also told him to cut feeding down from once a day to once every other day, and to try and limit how much time he had the lights on if at all.

Needless to say he still kept loosing fish. It seems like this tank is just destined to not have fish in it! He restarted it because he could not keep fish alive the first time around, and now he's loosing fish all over again.

Any input would be greatly appreciated!

[Crazygar]

Those fish you listed and pH, could be a part of the problem. Tetras, Cories and Gourami prefer a neutral to more acidic reading on the pH scale. 7.0 to 6.4 would be more optimal to keep those fish alive. The Swordtail on the other hand would just love that pH.

Also I noticed that the groupings are tiny. In a 55GAL tank, 2 of this, 2 of that, well it looks cool, but fish prefer to be in large schools of similar species (except Gourami). The more of their species the more confident the more happier they become the longer they survive.

I personally would start by making a list of the fish you want, determine the pH and go from there. Try using some RO water (20%) to start in your setup to help lower the pH a bit to get it to a more comfortable level if you are wanting to keep Tetras Cories and Gourami.

Gary

[lou zello]

i would skip the gouramis alltogether unless you can find a local breeder cause all the dwarf ones in the stores are terrible now days,other than that i would follow the advice allready given.