Angelfish issues

Firstly, I have more than one established, healthy and mature FW tanks. All get weekly water changes and maint., so I'm not really a "newb" at the FW aquarium thing anymore, but as with anything else, there is always more to learn.

I did research angelfish care prior to trying them and although my Ph is high (8.4), it's the same as the LFS where I regularly purchase my fish. I'm told their angels are domestically bred and not wildcaught; and they seem to do fine at the LFS. In spite of the matching Ph, I do still acclimate them slowly, as I do with all my new fish, always.

One of the first three that I bought is still looking and acting healthy, but the other two died within three days. I then went back and purchased three new ones, one of which died on day two. Now, a few days later, this morning two are not acting as healthy as I'd like...ie they are sort of just hovering near the heater and not exploring, picking at the plants and decorations, etc like they were before and I'm afraid they too will soon die.

The tank is a 29 gallon long with 2 small otos, 3 small honey gourami and 1 platy (perm. residents), plus 2 small "golden" algae eaters, which will be moved back to my 125 gal tank in a couple of days (they were temp. additions, to attend to some extra algae that had gotten away from my 2 otos a bit.) The angels are small juvies...about 1.5"-ish inches each.

Tank has plenty of plant (artificial) cover and hiding places to make them feel safe. There has been no observed aggression, either between the angels or from the other inhabitants. Ammonia = 0, Nitrites = 0, Nitrates = 10. Temp 78. Tank is in a quiet, low-traffic area and I do keep a small amount of aquarium salt in the water, as I do with all of my tanks.

Any opinions as to why I seem to be having trouble with them? Could it be that the very active (and highly amusing) algae eaters are stressing them out? Or, could it be they are just not truly healthy specimens in the 1st place? I've read that a small amount of salt should not bother them, but could that be false?

Any helpful answers and/or suggestions from some angel-keeping veterans would be greatly appreciated, as I do really want to keep a few of these beautiful fish, but not at the risk of unintentionally "killing" any more of them, if that's what's going on.

ty Star_rider for the reply.

Normally, I just very slowly (small amounts added over about an hour and 1/2 or so), add water from my tanks to the "travel" water, using a disposable cup, until the mix is mostly my tank water; and then net them into my tanks. But having read up on the angels, I am using drip method for them.

I do believe the goldens are Chinese, after researching online. I wanted the extra "tidy-up" crew for algae and needed something that could hold their own in a tank of largish semi-aggressives, as I added (stealthily or so I thought) six otos about two months ago and they were all immediately eaten up by the tanks' inhabitants; and plecos IMO just produce far too much waste for my liking. They are still small - about 2" - and for right now they are the most efficient algae eaters I've ever had, in addition to being fairly entertaining to watch.

The algae eaters' permanant home is my 125 gal, which has 2 - 7" leporinus f., 4 - bala sharks (ranging 4-7"), 1 - 5" Sc. Ahli, 2 - 4" Ice Blue Pseud., 1 - 6" Raphael cat, 2 - 5" Kenyi, 2 - 4" Synodontis e. and 4 - 4" dia. Silver Dollars. An ecclectic community I suppose, but they all get along very nicely. None too passive or too aggressive and they've been together a long time now (all raised together since very young and often school together - they all seem to like to school with the S.D.'s for some reason), so I'm in hopes the algae eaters will continue to get along ok in there. If not, they get a trip back to LFS. heh

I will try slowly raising the temp. up to about 83 on the tank for the angels; moving the golden alg. eaters back to the big tank and up my water changes on the tank for the angels to twice a week. Thanks much for your input! I hope it helps, because I really do love to watch the angels, but don't want to be responsible for any more deaths.

Ty Draal and Duke for your replies.

Looking at them again just now, they are larger than a nickel, but smaller than quarter...probably somewhere directly between. Maybe they are just too young/fragile. If I lose these, I will try once more with larger angels and see if I have more success.

Yes, the Ph 8.4 at home and at LFS is correct. I always ask when I purchase new fish, so I'm aware of any extra acclimation efforts that might be needed and they verified 8.4

At this very moment, they are all three swimming, picking at the plants, etc again and in about 15 min. I'm going to move the algae eaters back to the bigger tank. So in hopes maybe just temp. stress from the twitchy algae eaters and they will make it ok.

ty again.