first saltwater aquarium, weird 15g setup, many questions

my chiton died :(
it got flipped on its back and one of the snails got to it

also one of the snails died, also due to getting flipped.

these were both yesterday, and there have been no incidents since.
Unfortunately, that’s just part of the hobby.
 
by the way, tank update:
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the algae is getting worse, probably due to the sweet new light, but the snails are fighting it back. i wish i could tell them what to focus on lol. the nerites can make quick work of that fuzzy algae on the back wall, but then they just... seem to get bored after a few square inches. come on, guys!

the nerites also took a lot of the red (not coralline) algae off that biggest rock, within the first day. they're also seemingly bored of that stuff, and have not really touched it since.

the astraeas and florida ceriths are working on the very long hair algae on the rock with the most biodiversity! i can see my orange tunicate(?) again!
 
Looks good. Might be time to slow down on purchases and let things settle for a bit after the fish tomorrow.
 
ahh! i just saw another crab! maybe the "dead crab" WAS just a molt!
it seems to be eating algae, or some other tiny microorganisms on a rock. scraping its claws and bringing them up to its face.

it dwells in a pore in the rock, very hard to get a pic
 
ahh! i just saw another crab! maybe the "dead crab" WAS just a molt!
it seems to be eating algae, or some other tiny microorganisms on a rock. scraping its claws and bringing them up to its face.

it dwells in a pore in the rock, very hard to get a pic
Sounds positive.
 
hmm. it seems to be waving its little maxillipeds through the water to filter feed -which is the only reason i noticed it! i thought it was some kind of sessile invert, until i looked further down and noticed the claws- which makes it seem like a porcelain crab. however, it doesn't seem to have the claws for it:
Screenshot 2026-05-07 213402.png

they're hooked, and the top claw extends over the bottom. that seems to suggest a mithrax crab.
it is also hairy. light grey in color. very small, but i have no reference to measure.
 
hmm. it seems to be waving its little maxillipeds through the water to filter feed -which is the only reason i noticed it! i thought it was some kind of sessile invert, until i looked further down and noticed the claws- which makes it seem like a porcelain crab. however, it doesn't seem to have the claws for it:
View attachment 32418442
they're hooked, and the top claw extends over the bottom. that seems to suggest a mithrax crab.
Picture is too out of focus for me.
 
yeah, that's all he gave me to work with, went back into his cave shortly after. it does show the general shape of the claw (clinging sideways into rock, right is the top):
Screenshot 2026-05-07 214926.png
 
Maybe a pistol shrimp or mantis shrimp? Still can’t see anything in the pic lol.
 
it actually did seem to have the typical crab body plan, and i think its claws are both the same size! but i could be wrong, it strains my eyeballs just to look at the spot it's in.
for a moment it blended in but tucking its claws over its face, which i think is a very crablike thing to do.
however, we will never know for sure until this little diva comes fully out of its cave. i tried setting up my phone to take a video, and putting a little bit of presoaked pellet next to the rock... and it did come out to grab some! but the camera was at the WRONG ANGLE and didn't catch anything 😭

i didn't see, either.. i just saw it retreat back into its cave with its prize. backwards. so saw the exact same angle i've been seeing lol.

it is doing this kind of thing (not my video ofc) (also its maxillipeds are much smaller)
 
Definitely sounds like a crab then. Until I can see a better picture, I can't even guess what kind. Typically, those with "hairy" looking bodies and/or pointy pinchers are not reef safe. Those with "smooth" shells AND blunt pinchers are generally reef safe.
 
hmm. they doubled my order, which i thought was an optional thing. i think one of the wrasses might, in fact, be DOA but both gobies seem fine. ig i can take it in to my lfs if they fight?
 
hmm. they doubled my order, which i thought was an optional thing. i think one of the wrasses might, in fact, be DOA but both gobies seem fine. ig i can take it in to my lfs if they fight?
They doubled your fish order?
 
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