What was the temperature before you increased it to 30C?
Turn the temperature back down to 24C and get a broad spectrum medication that contains malachite green and treat the tank with that.
Do another big water change and gravel clean before treating with medication. If you can't get medication for a few days, do a 80-90% water change and gravel clean each day until you get the medication.
Make sure any buckets and hoses you use are free of chemicals and only get used on the fish tanks.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.
Turn the temperature back down to 24C and get a broad spectrum medication that contains malachite green and treat the tank with that.
Do another big water change and gravel clean before treating with medication. If you can't get medication for a few days, do a 80-90% water change and gravel clean each day until you get the medication.
Make sure any buckets and hoses you use are free of chemicals and only get used on the fish tanks.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.