Diagnosing My Betta Fish?

Tank
What is the water volume of the tank? 5.5 gallons
How long has the tank been running? 6 days
Does it have a filter? Yes - Aqueon QuietFlow Internal Power Filter Model AT10
Does it have a heater? Yes - Marina Submersible Aquarium Heater MinI 25W
What is the water temperature? Stays constant between 78-82 degrees F
What is the entire stocking of this tank? (Please list all fish and inverts.)
1 male veiltail betta, 1 mystery snail, 1 moss ball

Maintenance
How often do you change the water? Haven't done a water change yet since I got everything so recently, but I was planning to do a water change every other week
How much of the water do you change? Planning to do 25% water changes
What do you use to treat your water? Tetra AquaSafe for Bettas
Do you vacuum the substrate or just the water? I was planning to vacuum the substrate

*Parameters - Very Important
Did you cycle your tank before adding fish? No. I used API quick start and checked my water paramaters every other day since getting my fish; They remained constant relative to what's listed below
What do you use to test the water? API Freshwater Master Test Kit
What are your parameters? We need to know the exact numbers, not just “fine” or “safe”.

Ammonia: 0.25 ppm
Nitrite: 0 ppm
Nitrate: 0 ppm
pH: 7.4
*All parameters were checked 1 day before making this post*

Feeding
How often do you feed your fish? Once a day
How much do you feed your fish? 2 pellets
What brand of food do you feed your fish? Aqueon Betta Food
Do you feed frozen or freeze-dried foods? Yes - Freeze dried food once since I've gotten him

Illness & Symptoms
How long have you had this fish? 6 days
How long ago did you first notice these symptoms? Yesterday
In a few words, can you explain the symptoms? More lethargic, clamped dorsal fin, will sometimes hang out by the filter intake, possible signs of velvet?
Have you started any treatment for the illness? No
Was your fish physically ill or injured upon purchase? Not that I noticed
How has its behavior and appearance changed, if at all? No noticeable change in appearance, more lethargic since I have gotten him.

Explain your emergency situation in detail.

I got a new betta fish a few weeks ago, and I started to notice what could be early signs of velvet. He's becoming more lethargic as the days go on and has a clamped dorsal fin, but he still has a good appetite. He has what looks like the gold dust mostly on his face but I just wanted someone to confirm before I start medicating. I've included a video of him with flash and a picture of him without flash for reference.

If it does end up being velvet, any recommendations on medicating him that won't harm the moss ball and the mystery snail in the 5.5 gallon tank with him would be appreciated. Thank you!

Video:

 

Hello
You need to complete nitrogen cycle first fish needs nitrifying bacteria to leave healthy ..your Betta is sick from 0.25ppm ammonia level and stressed and there immunization system get's weak as your tank is only 5.5 gal 0.25 ammonia level is huge deal.. It doesn't matter what you do or adding chemicals to control it The nitrogen cycle is a funny thing in that means it’s going to happen whether you want it to or not. If you add your fish to an uncycled aquarium, the food and poop breaking down is going to introduce ammonia, which kick-starts the cycling process to fallow your water change that you do and you kick-starts the cycling over again and again than fish is suffer and die..

 

Any level of ammonia will be toxic to him. My guess is that’s his problem. As for velvet, I don’t believe he has it. Bettas are typically shiny and as long as he’s not flashing (rubbing against things) Id bet he’s fine. Velvet looks more like a copper dusting than a shiny gold. I would recommend using seachem prime to detoxify ammonia and nitrite while your tank is cycling, so it won’t hurt him if there’s up to 1ppm. You just have to remember to dose daily. The best thing to do would be to get some beneficial bacteria from an established clean aquarium, hopefully from a friend. So any gravel, filter sponge, or ornament. That would speed up the cycle significantly. If you’re like me and don’t have anyone into the hobby, you just have to keep his stress minimal during the process. Prime will help. Some people recommend bottled bacteria, but I’ve had no luck. It just feels like flushing money down the toilet.

I would also stick to weekly or biweekly water changes until the cycle is complete. Just keep a close eye on the ammonia and nitrite levels.

 

Any level of ammonia will be toxic to him. My guess is that’s his problem. As for velvet, I don’t believe he has it. Bettas are typically shiny and as long as he’s not flashing (rubbing against things) Id bet he’s fine. Velvet looks more like a copper dusting than a shiny gold. I would recommend using seachem prime to detoxify ammonia and nitrite while your tank is cycling, so it won’t hurt him if there’s up to 1ppm. You just have to remember to dose daily. The best thing to do would be to get some beneficial bacteria from an established clean aquarium, hopefully from a friend. So any gravel, filter sponge, or ornament. That would speed up the cycle significantly. If you’re like me and don’t have anyone into the hobby, you just have to keep his stress minimal during the process. Prime will help. Some people recommend bottled bacteria, but I’ve had no luck. It just feels like flushing money down the toilet.

I would not recommend to keep Betta in the tank during cycle making it worst what he needs now is fresh water is possible and change it every day and hope it will recover. one his tank finish cycle than can put betta back in tank.

 

Don't take the betta out of the tank, seeing as you don't have a separate cycled tank where he would be more comfortable that seems really pointless to me, and you'd need to replace him with some artificial ammonia source. Just leave him in and do daily 50% water changes and dose seachem prime until you no longer have ammonia or nitrite in the tank.