eeep! new fish is a casualty and i dont know why


pro stoner, newb reefer
Hi all
So I've been letting the hair algae grow a bit in my tank because i like the look and i've been planning on getting a lawnmower for a while, so i wanted to make sure he'd have enough to eat once he came. so I got one on saturday, acclimatized him nice and slow, released him into a little corner where he chilled and took a couple bites off the rock and it seemed all good. The next day, i noticed that my yellow goby and blue devil were acting strange, like not swimming around even though they knew i was feeding them (i feed once a day and they always, always come out.) So i thought they were just a bit stressed that this big ugly thing came into their territory.

One thing i noticed was that the lawnmower seemed to be breathing heavy. Then i noticed the blue devil doing the same thing, which it's never done before, nor has it ever missed a feeding or ever hung out in the bottom corner of the tank like its doing.

So then I come home today and the poor new lawnmower croaked :(. What makes it so much worse is that I can't figure out why, and now I'm scared the blue devil will be heading the same way.

I did every test I own, here's what i got
Trite/ammonia - 0
Nitrate - 15, a bit high but shouldn't be enough to kill a fish
Phosphate - 0 or very close to it. I'm assuming the hair algae takes some of it. I rinse my food and dont overfeed.
Ph - 8.0, the test is hard to read because the colours are off, but the LFS said it was 8.1-8.2 when i tested it there
Kh - 8.5
Calc - 380 (API test, horribly innacurate but its somewhere around there)
Salinity - 1.021, a little lower than normal, i try to keep it at 1.023
Temp - 82, yet that's after the light's been on all day, the heater is set at 80 so i'm guessing it fluctuates a bit. my roommates have said the alarm has gone off a couple times (meaning the temp was either above 82 or below 78, i wasnt there to check)

I realize everything's slightly off prime, but I've never had a fish die and would have never thought these params would be enough to off one. I've been doing 33% water changes the past couple weeks to try to tackle the high nitrates, but i changed the water 2 days before i got the new fish so the Ph or whatever else should have returned to normal. Is there something else it could be? I'll list everything that's changed/might be pertinent.

When i went to the store i also bought a new light - which turned out to be half the output i was looking for so i'll have to return it, but it's making my corals wilt a bit, so might this have something to do with fish metabolism/health?

I also bought a new koralia powerhead, the old one had come off its suction cups twice and blown up a pile of sand (will never buy another suction device, probably a contributing factor to the high trates.) I washed it before putting it in.

I'm rocking 2 powerheads and the protein skimmer, total GPH would be somewhere around 2000, or about 40x turnover. I don't have a sump or any other mechanical filter or UV light. I've been told live sand/rock and a protein skimmer are enough to keep things going.

I use instant ocean salt, with conditioned tap water. I've been thinking about switching to RO water from jugs from the store and conditioning it in case there's other stuff in there. Our water in Vancouver is mostly from snow melt, and is filtered extremely well - i've never heard of locals having issues with tap water. Maybe i'll look more into it.

Other than that I can't really think of other potential issues, other than some disease that i havent heard of. It seems to me the smoking gun is the heavy breathing, yet I've never seen the other fish breath heavily before, and the tank-raised clowns are as normal as ever. Could low oxygen levels be the culprit? Would an airstone help? (I've been told not to use them) Maybe something I don't test like magnesium?

Any help is appreciated, needless to say I have to figure this out asap before something else happens
It does sounds like it could be oxygenation... How much flow do you have in the tank with the new powerhead? If you don't already have a nice ripple flowing across the top of your water, then I'd suggest adjusting the powerhead to point more towards the top of your tank to better oxygenate.
yup, i put the sealed bag in the tank to adjust temp, then let water in 2 or 3 times to the bag to get him used to the new tank water. then when i let him in i dumped the whole bag full into the tank.

both my powerheads point slightly up towards the surface, and the protein skimmer return drops an inch or so into the tank and it creates a good wake and a bunch of bubbles.
NEVER dump the bag in! Every single time I dumped the bag water in it has ended in the death or at least one fish and the worst time all the fish I had in my tank.

I cant remember exactly what caused it (someone here explained it to me, but I forget) but it has something to do with the bag water becoming very nasty very fast. I usually acclimitate (sp) just as you do but in the end i net the fish out rather then pour.
whoa! how come this is the first i've heard of this?
i've done a little reading and some people say never dump the water in, others dont even mention it. the main reasons i've found in 15 mins of research are parasites from LFS water and ammonia build up in the bag. I can't imagine the ammonia being an issue once its released into the tank, so i'm going to hazard a guess at some parasite.
Yeh man never dump in the LFS water into your own, And alwys aclimate for atleast 45 min, I usually do about an hour, I use my turkey baister and add water to the bag slowly ones its doubled in water i use the baister to remove half the water from the bag, Then i continue adding water fro the DT to the bag untill its doubled again, then i remove fish by poring the bag into a bucket with my net over it to quickly grab the fish and put him in the DT. Thats the best way that works for me. In the case of fish that are prone to ich and stress i drip acclimate in a little bucket.
Two main reasons, the store you got it from could use copper based medications, and because of introducing a possible parasite into your tank. Always net your new additions.