Sorry it's going to be a bit of a long story because I'm not sure what or where went wrong. I'm just a few months into reefing.
[Tank specs]
Tank is about 90 gallons (it's a red sea max s-400). Temperature is currently set to 27C (slightly on the higher side, i know but the less my chiller has to work, the cheaper my bills ). My salinity is a slightly lower than 35 PPT. Reason being me having trouble getting the ATO to work in the beginning and somehow ended up topping off more water than I should have. But I've gotten help from a red sea staff who kindly helped me get the tank working properly. In any case, I didn't want to just spike the salinity up to 35 PPT immediately to avoid shocking the inhabitants, so i've been adding a bit more salt into my water changes gradually. It's about 33.5 PPT right now (used to be around 32 PPT). Skimmer and lights are the ones that came with the tank.
[My journey so far]
I started with a pair of ocellaris clownfish, a yellowbelly damsel, a cleaner shrimp and a toadstool leather. The yellowbelly tried to chase the clowns but when the clowns turn around the yellowbelly backed off lol. They're all about the same size (2-3cm). The toadstool was shy at first but later on started extending its polyps... and then stopped a few weeks later until now. The clownfish were small, so I think M/F hasn't been established yet. But one of them died a few weeks later, while the other one is still around till this day.
Then I added 6 blue eyed cardinalfish and a BTA. BTA walked around for a bit and settled down, still doing great and the clownfish hangs out in it. The blue eyed cardinalfish were pretty chill, just hanging around at one corner for a couple weeks... then suddenly they started dying off one by one every day... then stopped dying when there's 2 left. I suspect infighting but I didn't catch them in the act.
2 days ago, I added a pretty large sebae anemone, a tomini tang (about 5cm) and a foxfaced rabbitfish (maybe 6cm). Both the tang and foxface hung out at the back corner where the blue-eyed cardinalfish liked to hang out. The tomini tang was pretty healthy (shop owner said he's had it there for like 3 weeks) and acclimated quickly. The foxface wasn't doing so well by the time i got home, but today he seems to be looking healthy but hiding in a cave (i've read they are quite shy for the first couple weeks). Weirdly enough, the tomini tang died today.
[Current Issues]
With all that said, I've a couple issues that I hope people can help me with:
Blue-eyed cardinalfish. I suspect they were fighting each other. And potentially even the tomini tang? The dead fish that I picked up didn't look like they were chewed out or anything but I'm not sure. I've read they are pretty peaceful fish, so it could be either the clown or the yellowbelly damsel, both of which are known to be at least semi-aggressive. But all my fishes are pretty small (except tomini and foxface who are 5-6cm), so i don't think they're that territorial yet? The clownfish does have an anemone hosting so maaaaybe...?
Tank parameters. Fishes aside, the anemone are doing great. The toadstool, not so much. But i think it'll start extending its polyps again over time. I do intend to gradually fix the salinity, but temperature, I'm not sure. I did check online and all the inhabitants can handle 82F (27.7C).
Anemone not being where I want them. The anemone keep finding spots on the rockwork facing the back of the aquarium where i can't see from the front, so ideally i want them to move. I've been trying to get them to move by running a pump towards the back of the tank (heard they don't like places with direct flow), but so far no luck.
