Cut / indent in bettas headZ

[Emma1900]

Just found this on my betta this morning. What is it? Here is him and his tank.
I filled it this form to help you guys out
Housing:
How many gallons is your tank?
10
Does it have a filter?
Sponge filter
Does it have a heater?
Yes
What temperature is your tank?
79
Does your tank have an air stone or other type of aeration?
Airstone in filter
Does your Betta have tank mates? What kind?
2 nerite snails

Food:
What food brand do you use?
Hikari
Do you feed flakes or pellets?
Pellets
Freeze-dried?
Yes, bloodworms
How often do you feed your Betta? How much?
2 pellets 3 times a day

Maintenance:
Before your Betta became ill how often did you perform a water change?
1-2 times a week
What percentage of water did you change?
20%
What is the source of your water?
Tap
Do you vacuum the substrate or just dip out water?
Vacuum
What additives do you use other than conditioner? What brand of conditioner?
Prime and tank first

Water Parameters:
What are your water parameters? Please give exact numbers. If tested by pet store please get exact numbers. "Fine" or "Safe" won't help us help you. Important: Test your water before the regular water change; not after one.

Ammonia:0
Nitrite:0
Nitrate:10
pH:7.4
Hardness (GH):
Alkalinity (KH):

Symptoms and Treatment:
When did you first notice the symptoms?
This morning
How has your Betta’s appearance changed?
Cut/dent in head
How has your Betta’s behavior changed?
It hasn’t
Is your Betta still eating?
Yes
Have you started treating your Betta? If so, how?
Nope
Does your Betta have any history of being ill?
Only fin biting
How long have you owned your Betta?
4months
Was he or she ill or suffering some sort of damage when purchased?
No

 

[Colin_T]

It looks like a bacterial infection. You can try doing a big water change and gravel clean the substrate, then add some salt. Add 1-2 heaped tablespoon of rock salt for every 20 litres (5 gallons) of water. Keep salt in there for 2 weeks.

If it still looks red and inflamed 24 hours after the salt, get a broad spectrum medication that treats bacteria and fungal infections. You can use salt with the medication.