Disappearing Gobies

bsfmaximus · Jan 2, 2016

About a year ago I upgraded from a 29g FOWLR to a 54g corner and started off my first reef tank with some zoas. While still in the 29g long I tried to keep clown gobies (one or two at a time) and within a week they would disappear. Thanks to the affordability of these attractive fish, I went through trial and error 4 or 5 times before I gave up. Also during this year or so time period I had a blue damsel disappear. It should be mentioned, I had a decent sized sargassum angler at the time and I just chalked it up to her getting a number of decent meals.

Since then, the sargassum bit off more than she could chew and is no longer in the tank (RIP).

Since the sargassum died and now in the 54g corner, I didn't have any fish disappear for a while. A about 2 months ago I decided to try clown gobies again and within a few days, they too were gone. I had a psuedo in the 54g for about three months and it about a month ago it disappeared. What finally spurred me to ask for help - my diamond watchman randomly disappeared within the last two days. I have also noticed a small diatom bloom since I noticed the watchman missing (decomposing/nitrate spike?).

I keep my levels as consistent as possible and I use RODI water. 400 calcium, 10-20 nitrate, 0 nitrite, 0 ammonia, .25 phosphate, 8.2 pH. The only thing I notice changing substantially ever is nitrate. As a result I do a 10 gallon water change weekly. I have a RemoraS skimmer and a Cascade 1000 canister filter (which I also clean weekly with water changes). I have several coral and other tank mates and no one shows signs of being ill or distressed. Mushrooms, GSP, frogspawn, more zoas, toadstool, percula clowns, blue damsel, yellow tang, halloween crab, and a large brittle star.

I can say with some certainty that I don't think the gobies jumped out of my tank. I looked in every nook and cranny within 10+ feet. Do I have something in there I mentioned that would kill gobies specifically? Is there something I should watch for? I've included a recent picture of my tank. Any help, advice, input, and/or ideas are greatly appreciated!

eatbreakfast · Jan 2, 2016

What kind of brittle star? The green ones with yellow brittles are known fish eaters. In a tank that small a yellow tang may be guilty of harassing other fish. Also, a blue damsel will claim sections of the rockwork as hos own and attack any invaders to that territory.

Ligershark · Jan 2, 2016

Id say its probably a predator, albeit the starfish or another hitchhiker. Also nice aquascaping. I really like 54 corner tanks w the bowfront.

bsfmaximus · Jan 4, 2016

eatbreakfast said:
What kind of brittle star? The green ones with yellow brittles are known fish eaters. In a tank that small a yellow tang may be guilty of harassing other fish. Also, a blue damsel will claim sections of the rockwork as hos own and attack any invaders to that territory.

Thanks! It is a brown/black/grayish brittle star - nothing fancy. I've paid close attention to the yellow tang for any aggression and haven't seen any. That being said, who knows what goes on in the back corner of the tank that I can't see. Same with the blue damsel. I've never seen it nipping at other fish (which is why I have left it in there).

bsfmaximus · Jan 4, 2016

Ligershark said:
Id say its probably a predator, albeit the starfish or another hitchhiker. Also nice aquascaping. I really like 54 corner tanks w the bowfront.

Thank you! I do have a couple hitchhikers I've seen... very large, black emerald crabs. I am guessing they are emerald crabs at least. They are a lot hairier than emeralds and mostly black but the bodies and claws are nearly identical. Not sure if these could be the culprit but thought it worth a mention.

Congaken · Jan 4, 2016

bsfmaximus said:
Thank you! I do have a couple hitchhikers I've seen... very large, black emerald crabs. I am guessing they are emerald crabs at least. They are a lot hairier than emeralds and mostly black but the bodies and claws are nearly identical. Not sure if these could be the culprit but thought it worth a mention.

Similar problem with my yellow watchman goby...just gone (so far) for a week now...put him in from QT and the next minute he's gone...some members telling me he may be under the sand or a rock...still waiting for my goby to show...good luck...

Congaken · Jan 12, 2016

Happened to my yellow watchman...same thing...put him in from QT, harassed by yellow tail and spot tail blenny...went missing until I saw this little shriveled skin...I think that he gave up and died and was eaten by pistol shrimp or one of the cleanup...still looking for a fish that the two won't harass to death in my 10 nano...feedback is not hopeful...

human · Jan 12, 2016

bsfmaximus said:
Thank you! I do have a couple hitchhikers I've seen... very large, black emerald crabs. I am guessing they are emerald crabs at least. They are a lot hairier than emeralds and mostly black but the bodies and claws are nearly identical. Not sure if these could be the culprit but thought it worth a mention.

Sounds like a Gorilla crab, there's a good chance he's the culprit.

bsfmaximus · Jan 12, 2016

Sorry to hear that... my diamond watchman showed back up but seemed to be having issues breathing and was hardly moving. Within a day he was belly up on the sand. I didn't see any injuries. Perhaps you are right though about the gorilla crab.