Coral banded shark?????Im assuming your talking about bamboo sharks or coral cats.Both of those COULD grow out in a 75,but the bamboo will need a 300(or 400?)and the coral cat will need a 250.
Likely your not getting alot of respnse - because no one knows exactly what you mean by "coral banded shark". It's sounds like some hybrid of two different species of sharks - namely the Coral Catshark, and the Brown Banded Bamboo.
Also with sharks - the volume of the tank (gallons/liters) isn't as important as the tank's dimensions.
Thats a bamboo shark.Likewise,as mentioned above,dimensions are the most important.Chances are,the 75,125,and 300 are all square.What are the dimensions?I would let it growout for a short time in the 75 then just move it to the 300.
That's a Brown Banded Bamboo, to be exact. Which tends to average about 36-40", and can rech 42" in total length.
And it will likely reach 36" in about 4 yrs.
A standard 75 gallon (48" x 18" x 20") which would be able to hold a small pup for about 6-9 months with any real problems. And a Standard 125 gallon really isn't any wider than a standard 75 gallon - so that wouldn't be of any help
A standard 300 gallon (96" x 30" x 24") would only be able to hold a Brown Banded Bamboo for about 24-30 months. Any longer and it will likely start to get a bit tight too small for the shark.
Ultimately for a single adult Brown banded Bamboo shark - you would need a tank or pond of about 600 gallons (about 7' diameter) or more.