I hate getting into this redundant debate but it's like you said in your post,the dat in that small tank is of that size due to it's age and it probably didn't stuff itself with prey items, when it was free,anywhere near the amount that you claim to feed your dat.Most dats we see pictured probably are not as old as that one is......or was, because it was probably eaten sometime after that photo was taken.I don't know how old your dat is but I think we can agree that dats take on a certain look when they get up in age,just look at some NTT.....Pellets are about the best thing to feed dats but variety does not hurt either.