Serial Killer!

Hello 3Reefers!

We're new to marine tanks and their general ways of life. I have scoured the archives/search function and came up empty handed regarding our issue.

It appears that we have a shrimp serial killer on our hands.

Here's the background:

4 month old 125 gal. reef tank. 30 gal sump w/skimmer. +150 lbs live rock, cycled 2 weeks in and then started with a small CUC, then 1 week later 2 skunk/cleaner shrimp. waited 2 more weeks then a pair of Pec. Clowns.

We test for all the usual parameters, and all are WELL within spec. No copper has ever been used to dose for anything. Water is changed [40gal] every 7~10 days with fresh salt + buffer from the same LFS we have bought 99% of our set-up and live stock from. We have had 0 casualties with exception to the obviously busted up cleaners.


We have added 2~3 fish per week until our current stock of:

2x 1.5" Pec. Clowns
4x 1" fire gobies
6x Blue-Green Chromis [1"]
1x 3" yellow tang
1x Pigmy Flame Angel ]2.5"]
1x 3" Meluranus wrasse
1x 4" Diamond Gobie
~20 Zombie meat eating snails [Nasarius]
~20 >1" hermets
3 x >1" hitchhiker emerald crabs.

All of these dudes are doing WELL! Th ebad side is:

KIA:

4x +3" Skunk/cleaner shrimp [all cool until we bought and placed a preger's female three weeks ago]
1x Fire shrimp [for sure] 3"
1x Fire shrimp probably KIA 3" --unseen but it's a full moon, so?????

We come home after work today [still daylight] to find yet another shrimp whacked [the new/second Fire Shrimp bought this weekend]. At first we thought it was the Dia. Gobie since it started a week or so after he was placed in the tank. He is very industrious, and constantly working. He also eats hunks of silversides like there is no tomorrow. He is meaty food focused despite obvious algae in the sub-straight [live sand].

We feed two small feeding a day, mainly a blend of Marine Cuisine and Nori. As an attempt to satisfy the shrimp killer, we took our LFS advice and started with 1/2 a silverside each feeding. Obviously, the little guys go for the small stuff, and all of the +1.5"ers go for the meaty stuff.

I feel it's the Dia. Goby purely based on "if you can get it in your mouth..." My girlfriend thinks it's the remaining Fire Shrimp being competitive over resources.

What can we do to either isolate and ID the culprit, or somehow alter this aberrant behavior? I'm done with feeding some perp' $20 shrimp dinners!

Any help would be greatly appreciated.

Rob

 

It's possible you've got a malicious hitch hiker like a mantis shrimp. Are you hearing any clicking?

 

Defiantly sounds like a Mantis, check in holes on live rock and listen for clicking (it could be a spearer, silent, but that's highly unlikely)

 

Do you recall the times when you had the cleaner shrimp and fire shrimp together? Most fish don't touch cleaner shrimp but a fire/blood shrimp sure as heck will in a smaller tank.

Was there flesh inside the second fire shrimp. (In other words, I'm trying to determine if it might be a molt as opposed to a death).

BTW....it's not likely to be a mantis. With a mantis, you will never see a body.

 

those are pretty large water changes. Are you testing the salinity of the water you are adding compared to the water in your tank? shrimp are more sensative to changes in salinity than fish. probably even more so if they have recently molted. i would not trust that the salinity is what the LFS says it is without testing myself.

 

Didn't think of that, Mantis don't really leave a trace, if only your shrimp are affected, it could be the food, a better bet is the Chromis, I've seen those thing tear shrimp up.

 

I would start with the salinity checking.
Then I'd keep an eye out for the missing fire shrimp.
Also, just FYI, the Diamond Goby isn't much of an algae eater, so it's no wonder he's enjoying silversides LOL.

 

Look up saron(sp) shrimp. He may be your culprit. Try turning the actinics on 45min or so after lights out or use a red lense on a flashlight and look around for the culprit