Stingray not growing?

[Train]

I have 2 motoro stingrays that seem to not be growing I had both of them for just over a year now
Tank is 180 gallons feed shrimp krill tilapia feed once every day internal parsite?
Filtration is sump and fx5
I do x2 40% water changes a week
Top pic is when I got them and bottom pic is now.

 

[oldfish]

It is likely either they are not getting enough food to promote growth or not being kept warm enough or both. I would also feed young rays more then once per day if you hope to see growth.I feed all my rays at least twice a day and keep young rays near 80 F.

 

[Train]

Ok I've just started feeding alot more about a month ago in the begging I know I didn't feed enough thanks for the info

 

[KNH]

The marble is very nice looking and both appear a healthy weight now but have thin tails in the early pic. I'm guessing they are wild caught? I always feed young rays multiple times a day. 180g is pretty small for motoros. I had a marble male and motoro female and they reached 11" and 12" respectfully after 1 year. Good luck with them.