Fish Attacks-Need Opinions

[ccombs]

Hey!

So I am having some odd issues in my tank with new fish, and I am not sure what I am missing here. I believe my Lawnmower Blenny might be killing new additions to tank, what do you think based on the storyline below.

Tank Restarted After Disease-Completely Bleached, etc.
Cycled Per Lasse Method
Add Golden Head Goby
Wait A Few Months
Add Clown Pair
Wait A Few Months
Add Lawnmower Blenny
2 Months Go By
Clown Dies-No Sign Of Disease, Just Looked Beat Up (Clowns had paired, did all the weird shake stuff, etc.)
Wait 3-4 Months
Add Target Mandarin After Seeding Pods For Awhile
Mandarin Dies After 1 Week (He looked heathly and was eating, when he died he had a missing chunk of fin one morning)
Wait 1 Month
Add Tri Color Fairy Wrasse
Eats/Swims/Looks Very Healthy For 1 Week
Wrasse Dead This Morning

These fish that are dying have no fin rot, no spots, no signs of disease, eat like pigs, then boom, one morning they will turn up dead and appear to have been attacked. It is only new additions, it is not like existing fish are getting sick.

Could this be my LMB? He is about twice the size of anything else in the tank and swims around in a very dominate way, scares off other fish. Is he attacking these smaller fish? I am fed up with losing fish that I am very picky about adding. I know it is part of the hobby, but I HATE killing fish.

The biggest thing in common with all deaths is that they look completely healthy, and are eating very well, not acting lethargic. I will check the tank around midnight and see everybody doing ok, then they always turn up dead at around 7am the next morning. What is happening between midnight and 7am?

Here are parameters, everything is normal except my ongoing Nitrate issue. Corals seem to love the high nitrate though.

Salinity-1.025-1.026
Temp-79-80
Ammonia-0
Nitrite-0
Nitrate-40 (I know, I know lol. I am working on tank upgrades to resolve this now)

Other inhabitants are (2) Emerald Crabs, (5) Blue Leg Hermits, (1) Cleaner Shrimp, (1) Peppermint Shrimp.

@HotRocks @Big G @Hemmdog @mattzang @samnaz @dantimdad

Edit- Tank is 30 gallons BTW. Also, the Tri-Color Wrasse name is used for several scientific names of fish. This particular Wrasse was the 2-3 inch long one that can live in a 30, not the one that needs at least a 55.

 

[Big G]

You could be right. I have a Starry Blenny that was an absolute terror in the 20 QT and almost killed a pink spot goby, but later in the 90 DT, it's been fine and completely ignores the goby now.
How big is your tank?

 

[ccombs]

You could be right. I have a Starry Blenny that was an absolute terror in the 20 QT and almost killed a pink spot goby, but later in the 90 DT, it's been fine and completely ignores the goby now.
How big is your tank?

30 Gallon. When I got the LMB, he was a small dude, maybe 2-3 inches? Now he is over 4 for sure. I have never seen him 'attack' a fish. But he does dart into his cave and will swim right through anything in his way.

 

[Big G]

Might not be enough territory for the LMB to live peacefully. Fish are like cavemen. LOL

 

[ccombs]

Might not be enough territory for the LMB to live peacefully. Fish are like cavemen. LOL

Yeah, I certainly did not think he would get this big, he is pushing the max size on Live Aquaria for sure lol. The mandarin that died was also the one you took a look at with the potential bacteria infection awhile back, a post mortem showed absolutely torn up fins and almost like he took a shot directly on the back.

 

[Arthacker87]

I have a black sailfin blenny (I believe it's called that) that will fight with my tangs over food but other than that leaves everything alone. And honestly my tangs start it. Mandarins are tough to keep without established reef. Especially in a 30g. I've heard they can graze feed up to 30-40 pods a day or so they say. (What am I dr Seuss) it can deplete pretty quick. Maybe its the lawnmower I dunno. Just my opinion

 

[minus9]

LMB get big, probably too big for a 30g long term. I wouldn't always trust LA for pertinent information, you have to do a little more research and get a consensus on info in regards to size, minimum tank, etc.....
I would suggest an acclimation box for all future additions and keep them in there for at least three days minimum. If you find the LMB is being aggressive, then I would removes him and add the fish you want, then maybe reintroduce him afterwards.

 

[mattzang]

Yeah, I certainly did not think he would get this big, he is pushing the max size on Live Aquaria for sure lol. The mandarin that died was also the one you took a look at with the potential bacteria infection awhile back, a post mortem showed absolutely torn up fins and almost like he took a shot directly on the back.

i've never kept a lawnmower, but i did buy frags from a guy who had both a starry and lawnmower in the same tank and the lawnmower was HUGE. 6" at least? i did ask him how that dynamic worked and he said the starry was aggressive at first, but then the lawnmower just kept growing, so now the lawnmower rules the tank. it was a pretty massive tank, 6' 180 gallon type, but yeah i was floored. i've never seen a lawnmower that big

seems odd the lawnmower would try to attack non-herbivore fish, but who knows. gotta be that or some type of disease that the other fish are just immune to? shrug. blennies seem to vary in aggressiveness with a smaller tank possibly heightening the aggression. my midas is super peaceful, never seen him have any issues, but others say theirs just straight up attacks other fish. so you might just have a really aggressive one

 

[najer]

I have a starry blenny in my sump that killed at least one fish but when I saw it attack my flasher wrasse it made me wonder how many fish it had killed over a period of about 2 years, mystery deaths of healthy fish.
I would remove the blenny.

 

[samnaz]

Man, something’s definitely up but having no fish experience I have no help to offer here

 

[ccombs]

Thank you all for replies so far. I am not ruling out disease, but it is odd that they are all active, eating, and show no physical signs of an issue. I am unable to QT currently, but every addition is thoughtful. Every addition were at the LFS for several weeks for observation and the clown came directly from SA, which is pathogen free. I know that is not the same as a QT that you do yourself, but it does help lower risk by being wise about purchases.

 

[Oropher]

In my 10G frag tank, i have a Clown pair (3 years), a LMB for algae control (2"+, 1 year) and a 6line for pest control (6 months).

I took out a few corals from frag tank to put them in MT. A week ago, my wrasse jumped out and died. After that, clowns got territorial and female clown (half the size of blenny) always attack LMB everytime it gets out its "cave". LMB cannot fight back and run away.