Columbian Shark turning darker


I have 2 Columbian sharks (approx. 4-5” each) in a 200 gallon tank along with a silver arowana (approx. 9-10”). This is a temporary setup and will be putting the arowana in a 2,000 gallon custom tank once it’s finished so I can switch the sharks to brackish.

My issue is that one of my Colombian sharks has turned a darker coloration then previously or compared to his buddy.

This change occurred about 2 weeks during which he was still eating and acting normal.
However today when I fed them he seemed disinterested in any food, unlike his buddy.

I feed frozen blood worms and hikarI carnivore sinking pellets. (I’ve tried a range of shrimp to which both sharks show no interest.)

I am not sure if they need a brackish shift now or not as I am only told that they can stay in fresh while they are young.

Any information would be helpful these guys were the first fish I bought and would absolutely hate to lose them.

Thanks, Chris.
  • Thread Starter


Apologies I forgot to mention that I cannot have my water checked until the morning however I had it checked twice over 2 days ago in which both results showed excellent water peramiters.


They most definitely do much better in brackish water. You should see instant change in behavior once you put some salt in. They are more calm in brackish water.

Most photos, videos and links are disabled if you are not logged in.

Log in or register to view

Top Bottom