Mr. Fishie Not Doing Great?

[SerenityMarie254]

This is my grandma's Betta, and I just got here to find that he seems to have a lump on his upper tail?

I tried to attach a picture, lets see if that works.
It's wide and has white spots (doesn't look like the pictures of ich I saw online?) and the white is most noticeable on the one side and isn't anywhere else on his body.
I come down monthly to change his water completely because she is unable to do it on her own, and my uncle also keeps an eye on him, but hadn't mentioned anything.
Oh! And it has one of those non-adjustable heaters in his tank that fluctuates TOO MUCH and I have a new one that I brought down to switch it with this trip.
PLEASE HELP?

Housing
What size is your tank? 2.5
What temperature is your tank? 77.9 average but today it climbed up to 80.
Does your tank have a filter? No
Does your tank have an air stone or other type of aeration? No
Is your tank heated? Yes, non-adjustable heater I was planning to change tomorrow to an adjustable one
What tank mates does your betta fish live with? None, but he had a ghost shrimp friend that died a month back

Food
What type of food do you feed your betta fish? Betta Bits from Top Fin
How often do you feed your betta fish? Two pellets twice a day (two 'smaller' ones in the morning)

Maintenance
How often do you perform a water change? Monthly 100% weekly 25%
What percentage of the water do you change when you perform a water change? 100% monthly 25% weekly
What type of additives do you add to the water when you perform a water change? Top Fin dechlorinator

Water Parameters:
Have you tested your water? If so, what are the following parameters?

Ammonia: between .25 and .5 (tomorrow is cleaning day)
Nitrite: 0
Nitrate:20
pH:7.2
Hardness: 75
Alkalinity: 7.2

Symptoms and Treatment
How has your betta fish's appearance changed? My grandmother things his fin is "less flippy" (I think she means shorter but I don't think it looks like fin rot? But look at the picture above and let me know what you think because I'm pretty new to fish)
How has your betta fish's behavior changed? He seems aggravated to me, swimming fast. And he's been sitting on the rocks at the bottom more than he used to
When did you start noticing the symptoms? I noticed today, but it wasn't like this three weeks ago when I was last down. Grandmother says this is the first time she noticed, but not the best eyesight.
Have you started treating your fish? If so, how? Nope, just did the test strips.
Does your fish have any history of being ill? No
How old is your fish (approximately)? She has had him for 6 or 7 months (bought him at petsmart and he was full grown at that time?)

[Torshe]

Could it be a fungal infection? Is the white on his tail normal coloring? In a 2.5 gallon 100% change should be done about every 4 days. That might be why he got sick. I reccomend kanaplex, I got it from my lfs and its saved many of my bettas. Good luck!

[callistra]

Well it looks to me he's missing his tail and it' rotted away right down to his body.. can you take a sideways pic to get a better view?

Temp swings are a problem. They need to be stabilized. Do you know why it's jumping all over? You can get a 25w adjustable heater like Marineland Visitherm or Jager in something that size and there should be no reason it jumps on a good heater and a properly placed tank... unless her house is really that hot.

Something that size needs two water changes a week.. one 100% and one 50%. The 100% should include a through rinsing of the gravel to remove poop and other debris.

You can't have nitrates without a fully cycled or at least advanced cycled aquarium with filter. Unless your straight tap water has them.. Can you test it?

This is how to do large changes without shocking.

To do a water change, use a little cup like a plastic solo cup - this cup must be only for him and have never been used with soap or other chems. Scoop him up in this cup (keep him in the cup about 1/4 full of water - it doesn't need to be much because he won't be in it for long) and leave him in the cup while you change his water. To do the 50% use a turkey baster - dedicated only to him that has never seen soap or chems - and drag it through the gravel and try to suck as much of the poop out as possible, in addition to 50% of the water. Use a thermometer under the running tap to get it to be the same temp as the water that is normally in his tank. When the thermometer says the flowing tap is the right temp, fill back up his tank. At this point, add the conditioner (dose for how much water you change - if you change half the water you add half gallon worth of conditioner, If you do a 100% water change dose for the full gallon change). Float his plastic cup with him in it in the new water. Slowly add a couple tablespoons of the new water into his cup every 10 minutes for at least an hour. Finally, dump him in gently but try to get as little of the old cup water back into the tank as possible. When you do the weekly 100% you will do mostly the same thing except empty his tank fully and rinse everything in it very well under warm water but never use soaps or chemicals. Once it's fully cleaned/rinsed you can refill it and repeat the cup/acclimate phase.

[AyalaCookiejar]

I would get a liquid test kit. Sometimes there are nitrates in the water but I don't think they allow nitrates higher than 10 in tap water.. Although I guess it could be different depending on where you live.

Also, shrimp are super sensitive to water quality (which is likely why he passed). I'd do an immediate water change any time you see ammonia in any amount.