Something is killing my fish...

scoopsthedog · Apr 27, 2017

So I've had a Midas Blenny and two clowns for 9+ months and they are fine. Live in the front of the tank and are fine.

I then got a mandarin and after a week I saw this hole in him

It died quickly almost nuking the tank. I waited a few weeks thinking maybe a rock fell on it. I then got a small Goby and spotted dottyback. The Midas bullied the dottyback for a bit into the back of the tank and the Goby rolled towards the crevices. Next day. Gone. Then two days later.

So I have a serial killer in my tank. I have next to zero interest taking my entire tank apart and disturbing the sand bed. LFS suggested it could be a bobbit worm. Any ideas?

SunnyCoast Reefer · Apr 27, 2017

Im no expert but maybe you could attempt to lure what ever it is out with a piece of shrimp or meat and watch it at night possibly ?

saltyfilmfolks · Apr 27, 2017

ARRRG! dunno.
I dont recognize the bite marks.
#reefsquad

GHsaltie · Apr 27, 2017

Sounds like it's time for a late night stakeout. Marshmallows anybody?

Brew12 · Apr 27, 2017

I would bait a bottle trap and see what you get.

Brew12 · Apr 27, 2017

Maritimer · Apr 27, 2017

Have you got any crabs in the tank?

Coral banded shrimp?

That's a fairly frightening hole in that mandarin!

~Bruce

Zoarium · Apr 27, 2017

saltyfilmfolks · Apr 27, 2017

Maritimer said:
That's a fairly frightening hole in that mandarin!

yea thats a big mouth sneak attack.

3mm3 · Apr 27, 2017

If you think it may be a eunicid worm, have you found any areas around rocks that have what looks like slime or mucus?
Have any coral been chewed on?

BNR210 · Apr 28, 2017

I had this same thing happen to my canary blenny and my green mandarin, within 2 weeks of each other. [emoji22]

After I couldn't find a bobbit worm I removed my brittle starfish (that I had had for over 6 years) and nothing has been killed since.

Do you have one of these?

scoopsthedog · Apr 28, 2017

First off- love the community thanks for the feedback. I have an LED strip that can go full red so I'm planning a stakeout this weekend. The issue is under the cave I have a huge rock and there are so many places to hide. I have four shrimp - 2 skunk, 1 peppermint and 1 blood red- so I don't think Shrimp baiting will work as it will get eaten by the inverts first.
Haven't seen any slime or corals that look damaged.
No crabs. No coral banded.
How do I lay down the bottle trap?

Maritimer · Apr 28, 2017

If a bottle trap needs to be held in place, a rock or two inside should do it.

~Bruce

4FordFamily · Apr 28, 2017

Wow that's really something... I can't imagine a brittle star doing that I have two giants one bigger than my large hand (probably 30% larger than my hand) and one the size of a large hand. I've had them for at least 5 years. I know it's anecdotal but I don't think I've ever heard of brittle harming anyone like that, but admittedly I'm not an expert with inverts.

Best Fish-Jake · Apr 28, 2017

BNR210 said:
I had this same thing happen to my canary blenny and my green mandarin, within 2 weeks of each other. [emoji22]

After I couldn't find a bobbit worm I removed my brittle starfish (that I had had for over 6 years) and nothing has been killed since.

Do you have one of these?

Brittle stars wouldn't do that to your fish.. they would only harm a fish if it was very weak and/or threatening it (but it would probably try to run first)

tj w · Apr 28, 2017

Following.....

Vincent100 · Apr 28, 2017

Watching and waiting on this one ;Watching;Nailbiting

BNR210 · Apr 29, 2017

Best Fish-Jake said:
Brittle stars wouldn't do that to your fish.. they would only harm a fish if it was very weak and/or threatening it (but it would probably try to run first)

That's what I have been told but I still have my doubts.
Both the blenny and green mandarin slept in the sand at the front of the tank every night. They were both very heavy sleepers, they usually didn't really wake up until they were ready to. I could turn on the lights in the room after they had gone to bed and they wouldn't stir like the rest the fish in tank did.
I think that's how the brittle got them, while they were sleeping. Kind of like a fox can steal a sleeping chicken. Because both fish went to bed healthy and when I woke up the next morning (around 6 hours later) they were still laying in their sandy beds close to the glass with chunks eaten out of them.
The blenny hung on to life swimming around for the day but gave up the fight before lights out the next night.
He was the first to be hit and I thought it was a bobbit worm so I watched for many nights to show itself or signs that it was there. However I only saw the brittle moving around the sand bed at night, sometimes going to the blenny's sleeping spot. Two weeks later I found the green mandarin dead in his sleeping spot with a huge chunk eaten out of his side.
Since I hadn't seen any signs of anything else that could sneak up and start eating a sleeping fish and then slip away unseen besides the brittle I decided to remove it.
A month went by and nothing had attacked my sand dwelling Jawfish, so I decided to take a chance and save a spot mandarin that the LFS had had for a few weeks but was slowly starving in the store's copepod free tank.
It's been 4 months now and nothing else has been attacked or chewed on. The spot mandarin is plump and happy and ironically sleeps in the same spot as the green mandarin did.
I can't guarantee or prove that it was the brittle, and it may have just been a big coincidence, but I'm pretty in-tune with my tank, so unless something similar happens in the future I feel pretty confident that I caught the killer. [emoji16]

BNR210 · Apr 29, 2017

4FordFamily said:
Wow that's really something... I can't imagine a brittle star doing that I have two giants one bigger than my large hand (probably 30% larger than my hand) and one the size of a large hand. I've had them for at least 5 years. I know it's anecdotal but I don't think I've ever heard of brittle harming anyone like that, but admittedly I'm not an expert with inverts.

I know my thinking is from anecdotal evidence but my brittle was very large (around 12 inches) and I couldn't find anything else that could be causing these wounds. So I figured better safe than sorry, and so far so good.
One thing I have learned in this hobby is to remove questionable threats first and ask questions later. [emoji16]

Kershaw · Apr 29, 2017

scoopsthedog said:
So I've had a Midas Blenny and two clowns for 9+ months and they are fine. Live in the front of the tank and are fine.

I then got a mandarin and after a week I saw this hole in him

It died quickly almost nuking the tank. I waited a few weeks thinking maybe a rock fell on it. I then got a small Goby and spotted dottyback. The Midas bullied the dottyback for a bit into the back of the tank and the Goby rolled towards the crevices. Next day. Gone. Then two days later.

So I have a serial killer in my tank. I have next to zero interest taking my entire tank apart and disturbing the sand bed. LFS suggested it could be a bobbit worm. Any ideas?

Any chance these fish died from disease or infection, and then other critters ate on the corpse?
Not saying there isn't somthing attaching the fish just making sure all possible causes are being thought of.