Betta--possible fin rot but started on body--advancing quickly!

Hi all! I have a female Betta who has developed what I think seems like fin rot, but it started oddly and I don't want to treat her for the wrong thing. The first sign I had that anything was wrong was a patch on her side, on the back half of her body, that seemed lightly dusted in grey. Next her tail developed a dark grey edge. Today, about a week after the first signs, there are grey patches over the back half of her body, and the middle of her tail is missing...HOWEVER she's been in with a male, so her tail damage could be caused by disease or by him. The grey patches are more like a dusting than a solid colour. To me it looks like an ash-grey mold like you would see on a cheese. It is not fuzzy and she looked perfectly healthy other than that. She is a cellophane (translucent) Betta, so any change is very visible.
She has good reason to be stressed anyways, as I've been attempting to breed my two Bettas and she's been in with the male. As of tonight I have my boy jarred inside the tank. I do have a second tank hiding in the trunk of my car, as I didn't want my boyfriend to see that I'd overspent and bought TWO, and will set it up tomorrow so that I can properly separate them. Kitty is losing his mind stuck inside a jar while she explores around him. Yes, my male Betta is named Kitty. My girl is Birdy.

I am very new to fish, and learning through my mistakes unfortunately. Some things that I have done wrong:
-I have no idea what the water pH/ammonia/nitrites/anything requiring a test strip is. I have no test strips.
-the tank has not been cycled, and the filter is not currently running as it is only half-filled in my attempt to breed my two Bettas. I've read conflicting reports on whether to run a filter or not for that, as they don't like moving water.
-I did not properly condition my Bettas before putting them into the tank. I had only owned the female for a week. I did not feed them live foods
-I left the two Bettas together for 10 days rather than separating them after 3 and reconditioning them, as I have read. Initially I wasn't worried about them because she was putting him in his place and he was being very gentle with her, however he's gotten progressively more aggressive towards her. Fishy blue balls?
-I did not immediately attempt to heal her when the grey patch first appeared.

Tank size: 20 gallons, but only half-full for breeding, so 10 gallons of water..
Tank temp: 80 f

Volume and Frequency of water changes: About 50% once a week.

Chemical Additives or Media in your tank: I had added one of those bacterial tank cycle liquids, but seem to have managed to utterly lose it somewhere in the house, to the point that I've had to buy a new one (API StressZyme+, have not used it yet). At the last water change I did not add bacteria. I was trying to help her, and just added API Melafix "Treats bacterial infections".

Tank inhabitants: Two Bettas, one male and one female
Food: Aqueon Betta pellets, 4-5 a day as they have been especially active. Used to feed my male 3 a day. Occasional freeze-dried bloodworms.

Recent additions to your tank (living or decoration): Everything that is in it can be considered new. Currently in it, besides appliances: One chipped mug, lying on its side. Several rocks. A couple stalks of lucky bamboo. No substrate.

Exposure to chemicals: Shouldn't be any besides the Melafix I added.

Hi and welcome to the forum

Can you post a picture of the fish so we can clearly see the issue?

Grey patches on the body can be protozoan infections or fungus. Fungus is normally fluffy, protozoan infections just look like cream, white or grey patches on the body.

Melafix, Pimafix, Bettafix can leave an oily film over the surface that can suffocate labyrinth fishes (Bettas and gouramis). Make sure you have some aeration and filtration so the medication doesn't kill the fish.

All aquariums should have filtration to keep the water clean. Even breeding tanks should have filtration to keep the ammonia levels at 0 so it doesn't poison the adults or babies. An air operated sponge filter works well in most breeding tanks.

Don't Want to preach but this is not the time to try and breed. They need to acclimate to new homes and settle in. You have probably stressed this poor little girl to the max. As Colin requested, we need a pic before we can help attempt to diagnose. Until then, keep her alone in a quarantine tank. Keep her in dechlorinated fresh clean water. Daily water changes. Others may disagree but I would add a little aquarium salt too. One teaspoon in a 5 gallon tank is plenty for bettas. If you take 50% of the water out during a water change, add 1/2 the salt back in. We’ll go from here after a pic. The spot being gray colored and the tail rot worries me. Columnaris can begin with gray spots and it seems to be affecting a lot of bettas right now. It is a gram negative bacterial infection and will only respond to a combination of Kanaplex and Furan-2 together. It often begins internally and may be too late. I just lost 3 tanks to it. All bettas. Don’t panic yet though. It could well be a fungus which we pray it is. If so, the salt will help. Let’s get the pic so we can see and go from there.

Colin_T after your suggestion of protazoan infection I tried to take pictures of her in a flashlight beam.
Hard to hold the flashlight and camera, so it's not as obvious in the picture, but it does have a gold sheen. However she is not trying to scratch on anything, and for the most part her fins have been normal. She was holding them clamped a bit the last couple days that she was loose with the male, but seems to have relaxed them now that he's trapped away from her. The black on her tail, however, was did not glow at all, which makes me think that is a separate infection, and fin rot.

Colin_T
Thank you for the information on the MelaFix. I won't use it again. And I will be getting a sponge filter before attempting to breed again, whether or not it is these two fish--this could be retirement, depending on how long it takes to get her back to health and THEN condition her properly.
Deanasue
I realize that this was poor decision making on my part. I got too excited about putting them together, and didn't take the time to care for them properly. On the plus side, I don't think it's columnaris and I'm hopeful she can make a full recovery,

Prior to having these two fish, I haven't thought of fish as thinking feeling animals, which I am coming to realize. Like many people, I've thought of fish as semi-disposable living decorations. As I spend time with my Kitty and Birdy, I'm coming to see their distinct personalities and needs and wants, and feeling awful about how I felt about fish before. I hope that they and all aquarium enthusiasts accept my sincere apology for my lack of care in the past. I love these two Bettas very much and will be doing everything in my power to keep them both healthy and happy. Once I finish getting them set up today, they will each have their own 20 gallon tank with heater and filter and a stimulating environment.

Are you talking about the grey/brown scales? She looks alright to me and I do believe her tail fin is healing. Because you do not know if the tank is cycled I suggest you be doing every other day 50% water changes and move the boy to another tank ASAP and do the same with him until both tanks are cycled. You should invest in a good test kit as well. Fish keeping isn't cheap, I've spent so much on my aquatic children.

I think you should halt all plans of breeding them. You need to do more researching, gain some more experience, and get the tanks cycled before even thinking of breeding fish. Bettas are not a beginner breeding fish, their fry are tiny and need perfect water quality and microscopic live foods.

The tail looks more like nipped tail than tail rot. She actually looks fine to me. Clean water will heal the tail. Glad you are taking such good care! Careful or it will become an addiction like it has for most of us and you will have multiple tanks.

Did the fish have the black scales and black edge to the tail when you got her?
If not it is probably bruising caused by chemical burns and should clear up over a month or so.
The tail looks like it has been bitten but does not look infected.

If the fish starts rubbing on objects in the tank then it might have protozoan parasites but until that time do not add any chemicals to treat it.

Monitor the water quality for ammonia and nitrite and do big water changes to keep those levels low.

The following link has some information about breeding fish and culturing food for the babies. It takes a month or so to get most of the fry food growing well and you should condition the parents during that time.
http://www.fishforums.net/threads/back-to-basics-when-breeding-fish.448304/