The fish do not have neon tetra disease.
Neon disease is caused by a bacterial infection and causes the blue line to fade and go cream/ white, and the fish die within 24-48 hours of showing these symptoms.
Neon disease is sometimes seen on newly imported fish but is rare in established tanks that get regular water changes and gravel cleans.
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Are you talking about the black dots on either side of the red line next to the tail?
If yes, they don't look like any fish diseases I know of.
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The fish look pretty normal to me, although one is a bit skinny compared to the others. If it's eating normally then it probably has intestinal worms.
You can use Praziquantel to treat tapeworm and gill flukes. And Levamisole to treat thread/ round worms.
Remove carbon from filters before treatment and increase aeration/ surface turbulence to maximise oxygen levels in the water.
You treat the fish once a week for 3-4 weeks. The first treatment will kill any worms in the fish. The second and third treatments kill any baby worms that hatch from eggs inside the fish's digestive tract.
You do a 75% water change and complete gravel clean 24-48 hours after treatment. Clean the filter 24 hours after treatment too.
Treat every fish tank in the house at the same time.
Do not use the 2 medications together. If you want to treat both medications in a short space of time, use Praziquantel on day one. Do a 75% water change and gravel clean the substrate on day 2 & 3. Treat the tank with Levamisole on day 4 and do a 75% water change and gravel clean on day 5, 6 & 7 and then start with Praziquantel again on day 8.
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To work out the volume of water in the tank:
measure length x width x height in cm.
divide by 1000.
= volume in litres.
When you measure the height, measure from the top of the substrate to the top of the water level.
There is a calculator/ converter in the "How To Tips" at the top of this page that will let you convert litres to gallons if you need it.
