5 Gallon Tank Need help ! my beta has a black spot

my beta has developed a black spot in the middle of his fin overnight, i was thinking it might be fin rot but google says fin rot starts from the bottom of the fin then works it way up to the body but that hasn’t happened with my beta, my fish only has a black spot in the middle as i’ve noticed, anyone have any idea what it is ? any help or advice? the spots closest to his body is just his pattern but the black under them is new and i’ve had him for 6months now and this never happened befor the picture you see with the pineapple in the back was when i first got him and that spot was never there. he is not in a bowl anymore btw he i has been living in a 5 and a half gallon for a while now.



here is a better photo of the black on his fin

 

The black spot is likely just his colour shifting. The majority of pet store bettas will change colour and pattern during their life time and a large portion of white bettas will develop coloured spots- this is due to the marble gene.

On the chance that it's not I have some questions though;
Is the tank cycled?
What are the parameters?
Any change in behaviour or appetite?
Did you notice it slowly happening or did it seem to appear over night?
Does it appear to be spreading?

 

his tank does have a filter that runs day and night i’m not sure what parameters are, i think temperature right ? well his temp stays between 70-80 Fahrenheit, his appetite has been the same and i’ve only noticed that it appeared overnight and i’ve only seen it today so i’m not sure yet if it’s spreading

The black spot is likely just his colour shifting. The majority of pet store bettas will change colour and pattern during their life time and a large portion of white bettas will develop coloured spots- this is due to the marble gene.

On the chance that it's not I have some questions though;
Is the tank cycled?
What are the parameters?
Any change in behaviour or appetite?
Did you notice it slowly happening or did it seem to appear over night?
Does it appear to be spreading?

his tank does have a filter that runs day and night i’m not sure what parameters are, i think temperature right ? well his temp stays between 70-80 Fahrenheit, his appetite has been the same and i’ve only noticed that it appeared overnight and i’ve only seen it today so i’m not sure yet if it’s spreading

his tank does have a filter that runs day and night i’m not sure what parameters are, i think temperature right ? well his temp stays between 70-80 Fahrenheit, his appetite has been the same and i’ve only noticed that it appeared overnight and i’ve only seen it today so i’m not sure yet if it’s spreading

his tank does have a filter that runs day and night i’m not sure what parameters are, i think temperature right ? well his temp stays between 70-80 Fahrenheit, his appetite has been the same and i’ve only noticed that it appeared overnight and i’ve only seen it today so i’m not sure yet if it’s spreading

should i just leave him alone or go and buy fin repair

 

Alright so you're going to want to look into the nitrogen cycle first and foremost. It's the single most important thing when it comes to keeping aquatic pets. You'll want to get your hands on a test kit like the API Freshwater Master Test Kit. Strip tests tend to be less accurate and accuracy in the readings is important.
How often have you been doing water changes and how much water do you change? Have you been cleaning or changing the filter?

 

Alright so you're going to want to look into the nitrogen cycle first and foremost. It's the single most important thing when it comes to keeping aquatic pets. You'll want to get your hands on a test kit like the API Freshwater Master Test Kit. Strip tests tend to be less accurate and accuracy in the readings is important.
How often have you been doing water changes and how much water do you change? Have you been cleaning or changing the filter?

i change the water every 2weeks if the water is dirty before then i change it earlier and the filter is changed every month and i actually just been putting him in a holding bowl while i change all his water

 

i change the water every 2weeks if the water is dirty before then i change it earlier and the filter is changed every month and i actually just been putting him in a holding bowl while i change all his water

You don't actually have to change your filter unless it has carbon in it (which can just be removed by cutting into the fabric) and it can actually be harmful to do so. This is because the majority of the bacteria that process ammonia and nitrites is living inside of it. Without them ammonia levels will rise enough to cause stress and harm to anything living inside. The smaller the tank the faster this will happen- a 5 gallon generally needs a water change every week varying between 25-50%. You don't really ever have to change all the water in a tank unless there has been a breakout of a serious disease, fungus, or parasite. The reason why carbon changes that is because it is used in a filter to suck up things like medications. After a while it actually starts to leak everything it's absorbed back into the water- which generally isn't a horrible problem but can cause issues with certain fish or medications.
You will want to look up guides on how to do a "fish-in" cycle. This refers to allowing the tank to build up enough ammonia (and nitrites) to trigger and complete it's first cycle while also making sure the aforementioned parameters are low enough to be considered safe for your fish. There are lots of guides available here on fishlore but

I know this sounds like a lot and might make you feel bad, please don't beat yourself up over this. What's important is that you clearly care about your betta. Many of us come into this hobby with similar tales.

 

You don't actually have to change your filter unless it has carbon in it (which can just be removed by cutting into the fabric) and it can actually be harmful to do so. This is because the majority of the bacteria that process ammonia and nitrites is living inside of it. Without them ammonia levels will rise enough to cause stress and harm to anything living inside. The smaller the tank the faster this will happen- a 5 gallon generally needs a water change every week varying between 25-50%. You don't really ever have to change all the water in a tank unless there has been a breakout of a serious disease, fungus, or parasite. The reason why carbon changes that is because it is used in a filter to suck up things like medications. After a while it actually starts to leak everything it's absorbed back into the water- which generally isn't a horrible problem but can cause issues with certain fish or medications.
You will want to look up guides on how to do a "fish-in" cycle. This refers to allowing the tank to build up enough ammonia (and nitrites) to trigger and complete it's first cycle while also making sure the aforementioned parameters are low enough to be considered safe for your fish. There are lots of guides available here on fishlore but

I know this sounds like a lot and might make you feel bad, please don't beat yourself up over this. What's important is that you clearly care about your betta. Many of us come into this hobby with similar tales.

ohh okay this is VERY helpful thank you so much i appreciate it i will build up the money to buy all these things my fish needs, i am kinda new to taking care of my beta the right way so this information helps lots. Thank you

 

No problem, best of luck!