These fish are bagged in very small bag when shipped around the world. I mean in couple of inches of water max (not even half cup of water) in very small bags.
Anytime when purchasing s/wfish , always ask how long they had them. I usually would wait a week or more before purchasing. This would require good relationship with lfs and I knew few reputable lfs who would do such practices for s/w w/o being asked to hold the fish. they just keep them in area in dark until ready to be sold. Even then, there are unfortunate casualties at lfs or at someone's home. But higher chance of survival when done properly. including time wise.
Most of individually packed fish including f/w
GBR will lay on side when unpacked until recovers from either anaesthetic exposure or the water pressure differences. Some fish are shiiped in nickel and dime bag, socalled, with very little water. It's the lfs or one who unpacks these fish to
acclimate to
not just the new water but also pressures, temp, lights etc. I've seen/had fish lay on its sides for months before recovering or never recover from such (unfortunately).
Adding one fish with some LR would not elevate Ammonia (
NH3) and/or
nitrite (
NO2)
unless overfed. I have 10G Nano with local s/w (puffers, dottys, blenny) which I set up same day I brought from Ocean by using water and sand from ocean+ Dried Out LR w/ no what so ever elevation. I skipped feeding for few days and very carefully control the amt of food given. Just let you know I returned the fish except Seahorses and Lawnmower Blenny last weekend. Looking forward to set up 72 Bow this summer when I will catch more colorful s/w fish.
If the NH3 truly elevated to 1.5, others should/would show some discomfort so I would still recommend holding back any actions until you can solidly determine the elevation of NHH3/NO2.
If you have overfed due to addition of flame angel (I mean lots of leftovers which should be avoided) and feel that NH3 has elevated then do perform small but frequent PWC until stablized. that is if truly at 1.5
Hope all goes well.
PS: it is very common to see new hobbyist to think/assume the worst than it actually is when other says it maybe. Very true since been in hobby/ndustry for many yrs. Please dont jump the gun. Always reason before action!