Cleaner Shrimp w/ Black Spots - Crab Dinner

weeknd

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So I've seen some previous threads for black spots on cleaner shrimp but most of the pix I saw had spots much less pronounced than mine and on a live shrimp (RIP CShrimp). The cleaner shrimp, while alive, spent most of its time inverted underneath a large flat piece of live rock so I only got to observe him in the open a few times during feeding. Never noticed the black spots until today just prior to one of my emerald crabs taking him to his final resting place and posing for a picture (attached).

Not planning on replacing the cleaner shrimp anytime soon....would not have tried introducing it in this new of a tank but it was a gift (as were the vast majority of the other inhabitants....having a birthday fall 1 month after starting a new tank has been a gift and a curse). My main concerns at this point are 1) Should i be concerned about any of the other inhabitants of my aquarium succumbing to the same fate? and 2) Should I take away the crabs dinner? (Probably too late for this one).

Parameters: Sal 1.025, NH4 0 ppm, NO2- 0 ppm, NO3- 0-2 ppm, pH 8.0-8.2, kH 170 ppm, Temp 78.3 F.

Tank stats: 75 gal reef, 125 lb lr, substrate is mix of crushed coral/aragonite, 30 gal sump, 10X turnover, terminator II protein skimmer, 3 gal refu (ref mud/live sand base, 0.5lb lf, chaeto ball), HOB ML Emp 400 biowheel w/ carbon and biomax inserts, 3X 530 gph and 1X 800 gph powerheads with deflectors. 40 Watt LED lighting (will be upgrading as req'd by new reef intros) Age: 2 months.

Tank inhabitants: 2x juv clownfish, 1 drag goby, 1 flame and 1 cb angel, 1 foxface, 1 roy gramma, 1 spike urchin, 1 BT anenome, 1 fire torch coral, 12X CUC (mix of hermit crabs, snails and emerald crabs)

I'm aware that system parameters have a higher tendency to fluctuate in a new tank (especially for someones first tank). And I've read that cleaner shrimp are especially susceptible to these fluctuations (especially salinity). I have RO/DI auto-topping my sump to ensure constant salinity and the remaining water parameters in my tank have been stable for the past few weeks at +/- 5% of the levels listed above so assuming this may be a disease of some sort? Saw something on black spot disease but responses seemed to indicate it goes away with a few molts...anyone familiar with this?
 

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I'm not certain what happened to the shrimp, but does your dragon goby happen to be a sleeper goby? They don't do well in new tanks at all, they need more food.
How much do you feed the crab? It could be that the shrimp had black spot disease and would have been okay if the crab hadn't gone after it. Crabs are opportunistic, and emerald crabs are known to kill tankmates for food, especially in newer tanks without much established food. It could be that your shrimp was about to molt, your crab was hungry, they crossed paths, and the crab did what crabs do.
 
I'm not certain what happened to the shrimp, but does your dragon goby happen to be a sleeper goby? They don't do well in new tanks at all, they need more food.
How much do you feed the crab? It could be that the shrimp had black spot disease and would have been okay if the crab hadn't gone after it. Crabs are opportunistic, and emerald crabs are known to kill tankmates for food, especially in newer tanks without much established food. It could be that your shrimp was about to molt, your crab was hungry, they crossed paths, and the crab did what crabs do.

Had to google to confirm but definitely a dragon goby and unfortunately for me he doesn't seem to like how coarse my substrate is....adding an inch of sand tomorrow to help him out a bit. In terms of my feeding I do not feed the crabs seperately. For the tank I do pellets once a day (twice if the goby is swimming towards the surface or if the foxface comes out when I get back from work)....algae sheets 3 times a week...and frozen mysis shrimp once a week and I individually feed my BTA chopped up shrimp once per week.

any advice as to what I should feed my crabs to keep them on their best behavior? I'm also considering banishing them to my sump for a while....one will not leave my fire torch alone and the other one killed a crab in transit, ate a cleaner shrimp (which he may have also killed) and has been known to cling onto the rocks and try and catch fish as they swim by. i had no idea that emerald crabs could be such a pain...
 
Is the goby eating prepared foods?

Your crabs will attack things if they're hungry, and also if they just see something that's easily killed. I'd suggest permanently sumping them, along with a few rocks, as that's the safest option for your other critters. They eat dead things and algae, so feed them algae sheets and chopped-up shrimp a few times a week.
 
goby eats the pellets that I feed daily and sifts through the substrate for algae and food scraps. the crabs have been mia for 3 days now but I will try and catch them next time they show face. I chopped up some shrimp and plan to feed my anenome tomorrow. I'll toss a few bits to the substrate for the crabs as bait....or as a temporary peace offering to gain their trust again before I banish them
 
My pep shrimp has done this once before. It went away after the next molt. I think it's just a problem when molting the first time.
 
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