Michael
Do you have a more recent current photo?
One taken from above and the side?
Also please list feeding frequency and approximately how much each fish recieves per feeding. It would also be of a lot of help if you can post water parameters,
pH, Ammonia, Nitrite, Natrate, KH buffering, GH hardness, salinity....Etc...
As E_americanus stated this type degeneritve disorder is sometimes seen in older public aquarium fish. The cause has been largely determined to be dietary.
I personally have not seen this ever in a gar this young, so suspect water conditions more than diet.
Richard (Widely known as Brooklamprey also)