New Motoro, Need Advice

[Sicksthree]

Hello,
I just received a new male Marble Motoro Ray yesterday. Yesterday he ate a few pinches of nightcrawlers and about 18 redworms. He would only eat about 3-5 redworms at a time. He was swimming around actively and became a better eater at night with lights off as opposed to during the day. He is about 7". This morning he has buried himself under the sand and is breathing fast and deep.
He is skinny. Visible pelvic bones but no obvious forehead indentation noted at this time. I will post pics when I can figure out how to do so.
I bought him via online web store. He has not been quarantined to my knowledge. Seller sent video of him eating black worms.
Tank-150 gallons
Temp 79
Ammonia 0
Nitrate- 20
Nitrite- 0
I previously had a Reticulated for 11 years but passed a couple weeks ago. I mention this because the Motoro is acting a lot different than my Reticulated when I got him and it's been quite some time that I've had a new fish.
So, I ask your advice, does this sound good, bad, expected?
Should I dose for internal parasites? I worry because he does not seem strong enough to dose the tank. Any advice would help. Thanks everyone.

 

[CANAMONSTER]

Clean water, food, salt and low stress. IMO that's all you can do. I don't like any prescription drugs for my self so I don't like dosing meds in my tank unless fish is strong and healthy and life death situation. Just me.

 

[Sicksthree]

CANAMOST
Thank you for your reply. I'm trying and crossing my fingers. Just trying to stay in and ahead of the game. I value your thoughts.

 

[Sicksthree]

Just wanted to give an update. It's been two weeks now that I've had my marble. I decided not to prazi my tank because I did not see any abnormal feces being expelled. at first, he ate 2 tablespoons of black worms daily. Within a few days he accepted red worms and worked himself up to 20 per feeding twice a day. Within the past several days I have transitioned him to eating Nightcrawlers. He actually eats 4 per feeding now. I am glad to report that he appears to be well acclimated and is putting on weight! I appreciate Canamonster for your support. I will continue to post more progress in the future.