Severe trembling
Hi all, I saw something unusual yesterday and am concerned about it.  I have a Jackknife drum (Equetus lanceolatus), which is pretty unusual in itself.  I have had the fish since July '02.  I recently moved it to a new large (110) tank.  Yesterday I entered the room and startled the 3 fish in there, they all scattered and the jackknife went into some sort of convulsive trembling, similar to what clownfish do but far more violent.  I thought he was just going to drop dead right then and there.  The trembling lasted for 30-40 seconds and then he just snapped out of it and has acted normal for the past 24 hours, although he did not eat last night which is very unusual.  This fish has been a major chore to keep, I think they are rare in the trade because they are very delicate in captivity.
<These little croakers (family Sciaenidae) from the tropical West Atlantic used to be more popular in decades past... but have been largely supplanted with more exotic, less-expensive Indo-Pacific species in our interest>
  He has contracted and survived Brooklynella twice and the slightest stress ( like a water change or tank cleaning) will cause an outbreak of crypto.  This is the first time I ever saw this trembling behavior, any thoughts?  -  D
<I have seen this behavior (in the wild) and suspect it is "natural" and can imagine some "species and individual survival value"... a potential predator might be put off by the shaking... And agree with your analysis of the added stress from being moved, perhaps shocked by your sudden entry into the room. In the wild these few drums/croaker species are cryptic, reclusive as/when young, hiding out under overhangs, behind other structure. I also agree with your statement re their apparent susceptibility to disease as a function of stress... and would do my/your best to keep this at a minimum. Bob Fenner>

Re: Severe trembling
Hi Bob, thanks for the response.  I thought I might add the reason for my
interest in this species.  I lived in St Thomas for 12 years, it was there
that I developed reef keeping as a hobby.
<Ahh, visited there last year. Very nice, though dry island>
It wasn't the keeping so much as
the collecting that held my interest, we would typically go collecting on
weekends while releasing whatever we had taken the week or two before.  The
drumfish was by far my favorite, although the local species there was E.
punctatus, the spotted drum.  The related "high hat" ( E. acuminatus) has
been commercially farmed as a food fish (cubbyu) and so there is considerable
data on the breeding / rearing of the species.
<Yes>
  Also Moe reports that both
punctatus and lanceolatus have been bred in captivity.
<Yes, though not commercially. That is, not (yet) for the ornamental or food fish industries>
It is my hope to
obtain and keep a group of 6-8 of one of these species and attempt to
establish a captive breeding program, I think at the right price this could
become a very popular aquarium fish.  It is attractive enough, seems fairly
docile and so far appears to be "reef safe".
<Agreed, w/ the exception of small crustaceans>
  The specimen I have now is the
"test fish".
<Very well>
I'm sorry you missed the SDMAS meeting at my house last month, ask Jason
about it.
<He said it was a very nice gathering. I hope to see you out at another and get to visit your facility>
Not a lot of people around here involved with home based
aquaculture, I think people really enjoyed it.   -  David
<Be seeing you. Bob Fenner>

Croaker input
Respected  sir/madam
I  am  research  fellow, working on  seasonal  variations  in  protein  of  Johnieops  dussumieri (Sciaenidae) from  Karachi coast.
if  you have  any  information, article, research  papers,  please  send  me ,I  will remain  thankful  to you for  ever.
sultan uddin  research  fellow  Karachi  university    Pakistan  
<The only croakers we have information on are the three "drums" or "high hats" used as juveniles for aquariums (of the tropical West Atlantic). Bob Fenner>