11 replies to this topic

[Kellywags]

Hi Guys,

Noticed this section (my fave!) hasn't been too active of late, so thought I'd throw something in from our archive...

....a few years back while diving the Exmouth Navy Pier, I spotted this deformed looking trevally on consecutive dives. I eventually got a shot of him and emailed to a couple of marine biologist friends who couldn't provide me with much insight into the reason his spine is out of shape (ie what disease it has and whether similar to a human spinal abnormality)....I thought some of you smart cookies might be able to shed some light?

It would also be interesting to see any other shots/ vision of fishies with disabilities- this little guy was determined to keep up with all the other able-bodied trevally, what a little trooper huh?!

[loftus]

I'm not a marine biologist, but I would bet this is a birth defect. I would imagine that the rules of natural selection are no different for fish then they are for other animals and unassisted humans. If the defect is compatible with survival and 'keeping up' as your picture shows, then fish, like any other species, will get along. I have a blind poodle that walks around the house like a he's in a pinball machine, but as long as we put food in his bowl, he gets along.

[zan]

From what I can tell, deformed spines are quite common in many fish species, and I've seen a few in various aquaria. The causes apparently range from birth defects to vitamin C deficiencies, injury as a young fish or possibly a result of parasitic infection. I have a book somewhere in work about fish disease - I'll see if I can find anything in there when I go back.

[Paul Kay]

Smooth Hounds (UK small shark) tend to spinal deformity in aquaria - I'm not sure whether this is due to the constant swimming in a 'circle' as has been suggested to me by aquaria staff, but it seems common enough in this species and this does makes sense given the maximum size of any aquarium.

[Kellywags]

Hmm interesting pgk- maybe the aquariums need to be equipped with red and green lights and a DJ (like at the ice rink) to tell the fishies when to swim clockwise and then anti clockwise to stop them getting sore backs!

Seriously though, I am looking forward to hearing what zan discovers in his book!...I have become a bit posessed with this little trevally (as Wags will confirm!)

[zan]

I'm a girl!!

Unfortunately my book doesn't really have much more information. It mentions that spinal deformities can be caused by a parasite which can lead to whirling disease, but unless your fish is whirling, it's unlikely (if only all illnesses were so self-explanatory, eh?). Nutritional factors and genetics have been the reported causes in farmed fish (e.g. salmon\bass), so that might be something?

sorry I can't be much help! I'll let you know if I find out any more, I'm getting curious myself now

Zan

[pmooney]

I have observed a similar spinal deformity in Grey Reef Shark at Osprey Reef.
The shark is observed on a regular basis over the last 2 years . It is a regular attendee at our weekly shark attraction dive and appears to have no issues swimming or feeding.

The first time I saw it I thought that the shark was demonstrating a threat posture - lucky for me I was mistaken

Will try to find some footage and post it when I get back to Cairns.

Edited by pmooney, 03 January 2008 - 06:33 AM.

[zan]

Right, I've just had a chat with a friend who works in an aquarium and she says:

there are quite a few reasons i think. If they have been selected for farming and get to live older than they would usually they often get deformed, which is what happened to our cod. If they have been kept in a round tub from an early age and only swim round in one direction that can cause it too.

In wild fish, it's possible that some are prone to it. Sand tiger sharks have big problems with spinal deformities in aquariums but it has also been seen in the wild and nobody knows what causes it. Also, if a wild fish has damaged itself somehow that can make the spine deform as it tries to heal/correct itself.

hope this is a bit more help!

Zan

[Kellywags]

Thanks for that Zan, really interesting- so sorry for assuming you were a male!


Would be cool to see your shark vision Peter- I'll look forward to that when you get home!

[zan]

NO bother- happens surprisingly often!

Happy diving

Zan

[AllisonFinch]

I don't know about fish, but in snakes, once the egg is laid-it must remain totally immobile. If it is moved it may allow the embryo to reattach on another part of the shell and may cause a "kinking" of the spine which is noticeable at hatching.

Maybe the same can be true of fish eggs, that are meant to stay immobile.

[n@utilus]

ive got some pictures of deformed nudis...if i find the time i will post some..