Proaquatix lookdowns mysterious death

[BigAirHarper]

So, I purchased 3 Threadfin Lookdowns in juvenile state that are part of Proaquatix tank bred lookdown breeding program. Fish were 1.5-2". The arrived Friday and 2 died yesterday and the last one died today. They were in my QT of course. I hadn't yet treated the tank with anything as I was ensuring they were properly acclimated and eating. All were, and treatment was do begin this week. QT has been long setup and established for months. Water params were all in check (ammonia was my first thought) but proved to be zero. Other fish in the QT are a Harlequin tusk (Juvi 3") and mandarin goby. They show no signs of disease and are eating just fine.

So I examined each lookdown carefully. There was definitely no fin nips or lacerations, this tusk seems very wimpy and nervous all the time anyway. The lookdowns were active swimmers and loved to eat. There we no signs of ich/velvet, etc. Now, on the last lookdown that died, i saw what appeared to be a stringy substance (not worm like, it was wider, like that fake cobwebs you see around halloween time). Could that have been some sort of disease even though they showed nothing on the outside? I know velvet is a quick killer, but I've seen fish with velvet and it's usually obvious the fishes' health is going down hill. The last lookdown to die looked completely normal yesterday and ate well. Just wondering if anyone has any input as to what could be the cause of death.

 

[h2so4hurts]

How big is the QT? I always QT my fish in separate tanks to limit stress.

 

[BigAirHarper]

It's a 30L. Ok so I'm definitely thinking its a sort of disease. Both my Harlequin tusk and mandarin goby aren't looking good tonight. I don't know what sort of disease is spreading this fast without showing any sign of skin problems.

 

[RJT]

Did you notice any of the fish breathing, even a little bit, heavier than usual?

 

[BigAirHarper]

Yes, the HT appears to now be breathing hard. The lookdowns appeared perfectly normal.

 

[h2so4hurts]

I'd get those fish in a formalin dip fast as a precaution. 5mL ridIch+ per gallon of tank water in a separate bucket with heavy aeration for 1 hr. Do it again in 48 hours if the fish don't look better.

 

[MrTuskfish]

^^^^YES^^^^

And is ammonia still zero? What are you doing ti keep ammonia/nitrite under control?

 

[BigAirHarper]

Awoke to a dead HT this morning. Only fish remaining is the mandarin goby.

Well guys, I'm going to chalk this one up to a massive learning experience. I've dealt with ich/velvet/black ich etc in my years in the hobby. Luckily I QT, so it usually doesn't make it to the DT. My question is, what is your best guess and what caused this? Some sort of protozoan? I don't have ridich+ in my medication shelf, so I guess I need to get some so a formalin dip is an option when needed. I just haven't seen something kill this quickly. Even with really encompassing ich/velvet you can see it coming and treat it accordingly in my experience.

My QT has been long established so I have a pretty good water quality consistency. Ammonia still zero. In the infancy of the QT I would do constant water changes to keep water params in check. Now, I would just do 10G water changes on the 30G tank as needed.

All fish came from the same supplier, and the day the fish arrived, I had just completed QT'ing another fish. That fish is currently in the DT with zero signs of disease. So I'm led to believe, one of multiple of the fish I bought from the supplier were infected with some sort of disease and it spread rapidly. Really would appreciate so help and info on figuring this out so I can prevent it in the future. It's been a crushing experience.