Please help me feed my betta :<

I bought a beautiful red Halfmoon Betta last Sunday.
He sat alone in a 3 gallon quarantine tank for one week and I just added him to the main 40 gallon with month old Platy fry today (they're big enough to not fit in the Betta's mouth).
But during his time in quarantine, he was SUPER stressed, despite having the tank cycled, a HOB filter with a baffle, a heater, and floating plants for him to hide in. But there were constant horizontal lines (not to be confused with the vertical breeding stripes) across his face.
He totally faded in color, and he began to lose his fins. His fin tips are kind of white-ish and he just looks like a Veiltail now!
To top it all off, he has not eaten anything since the day I bought him.

I bought Northfin Betta Bits, then Hikari Betta Bio Gold, then San Francisco Bay Freeze Dried Bloodworms, and he still refuses to eat. I called the shop and they said they feed their Bettas with Hikari BBG though (bruh).
My water parameters are 0 ppm NH3, 0 ppm NO2, 10 ppm NO3, heated to 86 F.
The 40 gallon is not entirely heavily planted, 1/3 of the tank is, with Java Fern and Anacharis/Elodea. It's also Spongebob themed, so plenty of more hiding spots in the ornaments. Could I get some tips please?

I was told to give him time to settle, but it has been a week already and he was stressed all throughout quarantine. He looks so depressed that it's starting to make ME depressed and finals are coming up too. Right now, he's just hiding in Squidward's house. I guess because it's dark in there.
I seriously have no clue what I should do next. I just want him to get better and happily swim about, terrorizing the little fish. The only meds I have on hand are Kordon Rapid CURE and API Pimafix.

Edit: added list of meds on hand

 

Its always best to have your tank cycled 1st and 40 gallon tank for one betta? I heard you could dose Hydrogen peroxide on the fins with a syringe without the needle of course. Look it up in YouTube.

 

Its always best to have your tank cycled 1st and 40 gallon tank for one betta? I heard you could dose Hydrogen peroxide on the fins with a syringe without the needle of course. Look it up in YouTube.

Thank you for you advice but I couldn't find a credible source for the H2O2 treatment on YouTube, so I'm going to avoid it for now. It's a 40 gallon community tank: (20) month old Platy fry and 1 Betta. Also, it is cycled. I mentioned in my post that the water parameters were: 0 ppm NH3, 0 ppm NO2, and 10 ppm NO3.

 

You will have to be a little more patient as it can take several weeks for any fish to get used to such a large area of aquarium. You stated that its not overly planted and that you have ornaments and so forth. That is all fine but he has gone from a cosy cottage to a huge great big mansion of an aquarium, he's probably feeling insecure and maybe a bit intimidated with all the wide open space and things he does not recognise....that insecurity will stop his interest in food.

You will need to give him alot more time to find his bearings, maybe add ornaments/plants from the QT aquarium for comfort. It can take several weeks for a fish to become secure and comfortable in a new aquarium, especially a lone little Betta in such an enormous (to him) space.

Give him time, make him comfy and secure and he should be fine....don't rush things, be patient with him cos he is just a bit frightened by all the space.

 

Probably already weak from the quarantine tank.....Don't have any solutions unfortunately, hopefully yours will make it

 

You will have to be a little more patient as it can take several weeks for any fish to get used to such a large area of aquarium. You stated that its not overly planted and that you have ornaments and so forth. That is all fine but he has gone from a cosy cottage to a huge great big mansion of an aquarium, he's probably feeling insecure and maybe a bit intimidated with all the wide open space and things he does not recognise....that insecurity will stop his interest in food.

You will need to give him alot more time to find his bearings, maybe add ornaments/plants from the QT aquarium for comfort. It can take several weeks for a fish to become secure and comfortable in a new aquarium, especially a lone little Betta in such an enormous (to him) space.

Give him time, make him comfy and secure and he should be fine....don't rush things, be patient with him cos he is just a bit frightened by all the space.

Thank you. You're right. I guess I have been a bit impatient. I was just worried for his health.

Probably already weak from the quarantine tank.....Don't have any solutions unfortunately, hopefully yours will make it

Thank you! I hope so too! The reason why I was so shocked was because he looked absolutely stunning in his little cup at the store. But as each day went by at home, he kept looking worse and worse.

 

Thank you for you advice but I couldn't find a credible source for the H2O2 treatment on YouTube, so I'm going to avoid it for now. It's a 40 gallon community tank: (20) month old Platy fry and 1 Betta. Also, it is cycled. I mentioned in my post that the water parameters were: 0 ppm NH3, 0 ppm NO2, and 10 ppm NO3.

I apologize for that here's the link

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I apologize for that here's the link

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Thank you for going out of your way to find the video for me! I decided to just provide my Betta with as much clean water as possible. I just put him alone in a heavily plastic-planted, 20 gal tall. His fins don't look tattered anymore, but he still has stripes and still hasn't eaten yet. Oof, how stubborn. Thank you for all your help though!

 

to get him to eat, you could try soaking his food in garlic juice it is a appetite enhancer.