Colu

Yes treat maracyn or maracyn2 which one you have to hand

As your still losing fish I would also do a course of maracyn2 in food feeding a small amount twice a day for 7 days just in case there's a bacterial component to the death's and add an extra air

They don't look great looks what I would do is treat with aquarium salt 1 table spoon for 2 gallons and do a course of maracyn2 leave the salt at that level for a week just remember to put back in what you take out so if you do a 10 gallon water change put 5 table spoons of salt back in to keep the salt at the required level @NickG83

I would add a small amount of aquarium salt to the tank 1 table spoon for 7 gallons that won't harm the plants at that level and Will aid Gill function and add essential electrolytes

I would do a third course of Expel p and monitor

Sorry to hear that I would keep a close eye on your other goldfish just in case something other then swim bladder is going on @Coby Sight

When you say parameters should be ok have you tested for ammonia nitrite nitrate pH

I would just leave the temperature were it is and it would be worthwhile adding an extra air @Coby Sight

Possible he has swim bladder what I would do is fast for a couple of days as swim bladder can be caused the fish over eating and the stomach putting pressure on the swim bladder or constipation and do Epsom salt baths 1 table spoon for 1 gallon for no more than 15 minutes for 5 days as Epsom salt acts as a muscle relaxant to help relieve pressure on the swim bladder give an update in 5 days if your seeing no improvement @Coby Sight

Keep treating Aquarium salt and ick x till maracyn2 arrives do the medicated food and ick X

It's called scoliosis it's really common in guppies due to low genetic diversity@Guppysnail

You want to use maracyn2 to kill the gram negative bacteria epistylis feeds off maracyn predominantly treats gram positive

The spots look raised correct me if am wrong if they are raised your could be dealing with epistylis it feeds off of gram negative bacteria on the slime coat of your fish and spreads more quickly at higher temperatures causing secondary bacterial infections that's what usually kills your fish he's how you tell the difference between ich and epistylis if your dealing with epistylis you want to treat with maracyn2 in food feeding a small amount twice a day for 7 days and dose the tank with ick X or aquarium salt as you have live I would use ick x @Evan

What I would do is test daily for ammonia and nitrite and do a water change if your test shows any and add a double dose of prime to help detoxify any ammonia or nitrite till it constantly stays at zero I would recommend treating with aquarium salt 1 table spoon for 5 gallons at that level it shouldn't harm your plants for 1 week give an update after a week if your seeing no improvement or the spots get worse

What are your water parameters ammonia nitrite nitrate pH temperature

Definitely a Ramshorn snail really good at eating dead plant matter and algae as long as your not over feeding the tank you shouldn't see a population explosion

I would move to a quarantine tank if you don't have one you could use a breeder box

It could be a number of things such as an injury causing hemorrhaging or a growth or a bacterial infection what I would do is quarantine and add some Indian almond leaves as they have antibacterial and antifungal properties depending on the quality of the leaves you might have to add one leaf per gallon to get a beneficial effect and I would add some aquarium salt 1 table spoon for 3 gallons I wouldn't go above that level with salt as Cory's are more sensitive to salt for a week give an update if it start to get worse before then@MNora

Looks like a change to the tissue this could be caused by a benign growth or an infection I would start to increase water changes as you have nitrite of 0.5 add a double dose of prime prime till it constantly stays at zero I would also do a course of maracyn2 in food feeding a small amount twice a day for 7 days active ingredient minocycline is a broad spectrum antibiotic and has anti-inflammatory properties @JohnPlecostamos

White patch on the mouth can be caused by mouth rot often associated with columnaris or a fungal infections what I would do as its not eating is quarantine if you can and treat with a combination of aquarium salt 1 table spoon for 2 gallons and do a course of kanaplex just in case there's a bacterial component @Hally M.

What are your water parameters ammonia nitrite nitrate etc

Hole the head is can be caused Hexamita and nutritional deficiencies the most effective treatment is metronidazole that the active ingredient in seachems metroplex so I would do is a course of seachems metroplex in food feeding a small amount twice a day for upto 3 weeks and feed a more varied diet

If it's just change to the colour of the scales that can be natural colour change as bettas age it not uncommon for them to change colour if its raised black spots then something else could be going on its difficult to tell of your picture if the black spots are raised @Ivory142

As it's only on one side your more than likely dealing with an internal growth could be a possible fatty cyst or a benign or cancerous growth what I would do is monitor if it's eating ok and and not showing any signs of deterioration I leave it be for now try and see if passes anything just to rule out an internal blockage

I can't tell off that picture if the spots are flat I would keep treating with ick X and I would add a small amount of aquarium salt 1 table spoon for 5 gallons as Ich causes massive electrolyte loss and the salt will add back in essential electrolytes if there raised you could be dealing with epistylis I would treat with a combination of ick X and do a course of maracyn2 in food feeding a small amount twice a day for 7 days as epistylis feeds off of the gram negative bacteria on the slime coat of your fish and spreads more quickly at higher temperatures @Zac