Aussie Marble Catshark on hunger strike

[Fin Jackson]

Hi everyone,
Not to sure what is up with my Aussie Marble Catshark, about 45cm long, who I have had for around 2 months eating perfect. About 3-4 feeds ago, her appetite severely decreased to where she hasn’t eaten in the last 2 feeds at all. I usually feed every 3 day a mix of either; a whole chopped baby octopus, bottlenose squid, raw prawns or high iodine fish off cuts like salmon or cod from the local fish market. Tank is kept at 25 degrees Celsius, but even in summer with a chiller it creeps up to 26.5 on warm summer days (35 degrees plus outside temp). Originally added due to not being able to keep enough nutrients in the water, which is tested 2-4 times daily via trident for cal, all and mag, daily for salt, and weekly for ammonia, nitrate and phosphate. Last nutrient test showed 0 ammonia, 0 nitrite, 19ppm nitrate, with 0.2ppm phosphate. Tank is run with a dKH of 8.5, calcium of 475 and magnesium of 1400. She is currently in a Cade 1800, not very active during the day but likes her late night swims around her cave. Would live shrimp help increase her appetite? I don’t think it is goiter as there’s no visable swelling around the thyroid gland, and I’m sure any swelling would have made itself noticeable after the 12 days of really decreased appetite.

 

[KrisReef]

When a fish is in captivity it can easily become stuffed with the huge Thanksgiving sized meals that we’ve decided that the fish should eat to be properly feed.

What are the nitrate and phosphate levels in the tank? I expect that the fish is busy trying to assimilate the food it has eaten.

 

[Jay Hemdal Verified Community Expert]

Hi everyone,
Not to sure what is up with my Aussie Marble Catshark, about 45cm long, who I have had for around 2 months eating perfect. About 3-4 feeds ago, her appetite severely decreased to where she hasn’t eaten in the last 2 feeds at all. I usually feed every 3 day a mix of either; a whole chopped baby octopus, bottlenose squid, raw prawns or high iodine fish off cuts like salmon or cod from the local fish market. Tank is kept at 25 degrees Celsius, but even in summer with a chiller it creeps up to 26.5 on warm summer days (35 degrees plus outside temp). Originally added due to not being able to keep enough nutrients in the water, which is tested 2-4 times daily via trident for cal, all and mag, daily for salt, and weekly for ammonia, nitrate and phosphate. Last nutrient test showed 0 ammonia, 0 nitrite, 19ppm nitrate, with 0.2ppm phosphate. Tank is run with a dKH of 8.5, calcium of 475 and magnesium of 1400. She is currently in a Cade 1800, not very active during the day but likes her late night swims around her cave. Would live shrimp help increase her appetite? I don’t think it is goiter as there’s no visable swelling around the thyroid gland, and I’m sure any swelling would have made itself noticeable after the 12 days of really decreased appetite.

I don't see anything in your parameters that would account for this. Can you post a video of the shark's head taken under white lights? That can help me judge its respiration rate.

Jay

 

[Fin Jackson]

I don't see anything in your parameters that would account for this. Can you post a video of the shark's head taken under white lights? That can help me judge its respiration rate.

Jay

Sure thing will do when lights come on tommorow.

 

[Fin Jackson]

When a fish is in captivity it can easily become stuffed with the huge Thanksgiving sized meals that we’ve decided that the fish should eat to be properly feed.

What are the nitrate and phosphate levels in the tank? I expect that the fish is busy trying to assimilate the food it has eaten.

I’ll do a test in the morning and get back to you asap.

 

[Fin Jackson]

I managed to get her to eat 2 thin slices of salmon tonight, not a lot at all but it’s giving me hope. Fingers crossed

 

[Fin Jackson]

Here is a video, but hard to see but I’ll try get a better video.

 

[Jay Hemdal Verified Community Expert]

Here is a video, but hard to see but I’ll try get a better video.

Sorry - no video attached.

 

[Fin Jackson]

Ah ok, I’ll try to upload to YouTube.

 

[Jay Hemdal Verified Community Expert]

Ah ok, I’ll try to upload to YouTube.

It's breathing oddly to me - the gilling rate is about 60 per minute, which is a bit high, but what I don't understand is that the fish is making very fast gill cycles - the gill flaps open and close very swiftly. I've never seen a shark do that before. So - let's say a shark is breathing at one gill beat per second - normally, the gills slowly open and slowly close, taking up most of that second. In your shark, the gills open and close in a flash and then the fish is still for the remainder of the second. I'm not sure what to make of that other than it is having some issues with breathing. Does the tank have ample aeration, not just circulation?

Jay

 

[Fin Jackson]

Yes, the tank is fully aerated, heavy flow and oversized skimmer but I can always add air pumps and such if required. That video was probably taken 15-30 minutes after a waterchange, I’ll take another today now a day has passed. Could the waterchange cause the breathing issue as flow is turned off?

 

[Jay Hemdal Verified Community Expert]

Yes, the tank is fully aerated, heavy flow and oversized skimmer but I can always add air pumps and such if required. That video was probably taken 15-30 minutes after a waterchange, I’ll take another today now a day has passed. Could the waterchange cause the breathing issue as flow is turned off?

Yes - any tank work has the potential to case fish extra stress, but that should settle down after a few hours.

 

[Fin Jackson]

Thanks for the reply Jay. Just a quick update, she ate half a baby octopus tonight and a whole vitamin enriched large green prawn very eagerly. Hopefully she is recovering. Quick question though, is it normal for a Catshark to only accept food after lights out, the whole time I have kept her she refuses to eat during the dusk period of day but will gobble down at night. Is she more likely to stick with her natural instinct or will she adapt to daytime feedings. Below are 2 pictures of the system taken earlier today incase you are interested.

 

[Fin Jackson]

What are the nitrate and phosphate levels in the tank? I expect that the fish is busy trying to assimilate the food it has eaten.

Nitrate came back at 16ppm and Phosphate came back at 0.2ppm. Been pretty stable around these values for the last few months and finally keeping nutrient in the water for the coral.

 

[MDAquatics]

I don't know much as much about sharks as others beacuse I've never kept them. I do however consider myself a student of them. I agree completely about the breathing. That fish does not look like its breathing normally. You said you've basically eliminated goiter. What about a bacterial infection? Hows its buoyancy? These are definitely known to cause breathing issues. Do you have a longer video? Or a video taken since its started to eat a little better. Maybe its resolving itself.

https://akjournals.com/view/journals/004/72/4/article-p235.xml

 

[Jay Hemdal Verified Community Expert]

Thanks for the reply Jay. Just a quick update, she ate half a baby octopus tonight and a whole vitamin enriched large green prawn very eagerly. Hopefully she is recovering. Quick question though, is it normal for a Catshark to only accept food after lights out, the whole time I have kept her she refuses to eat during the dusk period of day but will gobble down at night. Is she more likely to stick with her natural instinct or will she adapt to daytime feedings. Below are 2 pictures of the system taken earlier today incase you are interested.

This genus is very nocturnal. I've gotten them to adapt better to feeding during the day, but only if I put the food right in front of them. They otherwise tend to spend their day just sitting still under ledges or next to rocks.

I looked up some videos online to see if I could get a baseline respiration rate for this species. I did find one video of a shark that was breathing like yours is, so I'm thinking that this rapid gill movement isn't abnormal for this species, but the 60 beats per minute in your fish is still a bit high.

 

[Fin Jackson]

I

I don't know much as much about sharks as others beacuse I've never kept them. I do however consider myself a student of them. I agree completely about the breathing. That fish does not look like its breathing normally. You said you've basically eliminated goiter. What about a bacterial infection? Hows its buoyancy? These are definitely known to cause breathing issues. Do you have a longer video? Or a video taken since its started to eat a little better. Maybe its resolving itself.

https://akjournals.com/view/journals/004/72/4/article-p235.xml

I haven’t ruled out goiter it just seems very unlikely given the symptoms, but I agree that a bacterial infection is very much possible.

I got another video of her when she is resting during the day, same sort of gill respiration rate it seems.

 

[Fin Jackson]

Sorry it keeps not sending the attached videos