Obviously it is a water problem cuz I am too busy and didnt make water change for 3 weeks
now I have all my fish in a good quality tank treating with melafix and salt
they have ick and red on tail and skin
the red is under skin and look likes bleeding inside in blood vessels
Is that a parasitic disease?
I have deal with ick before but I am not sure if the red thing
Can melafix with salt cure them?

That sounds like septicemia I to me - an infection and you will need antibiotics. Kanacyn should work.

Make sure you have no ammonia and nitrite.

How long has your new tank been set up. Did you read about cycling?

Good luck!

shj

my tank has been set up for almost 4 months
I have no idea about cycling but I do keep no ammonia and nitrite
I have found out that there are many white worms from tap water, are they harmful and how can I get rid of them

Are the little white worms a few millimetres long and do they stick to the glasse tc? If so they are planaria and are completely harmless to your fish. However, they are a sign of overfeeding and poor maintenace. DO a few good water changes and vacuum your gravel thoroughly and you should get rid of them gradually.
The red marks do sound like septicimia so you need to treat with an anti internal bacteria medication quickly. Check your water parameters and make sure your ammonia and nitrite are 0, and nitrate under 20.
I'd use aquarium salt to cure the ich as well. Add a teaspoon per gallon (dissolved in a glass with a little tank water), then 12 hours later add another teaspoon per gallon, then repeat again in another 12 hours. Keep this strength of solution in your tank for 2 weeks, increase the temp to 80 by a degree a day and turn the tank lights out. This will wipe the ich out. Remember that if you do water changes you'll ahve to add more salt to compensate for the new water being added, so if you add 3 gallons you will need to add another 3 tablespoons of salt.

thanks for the replies
those white worms are not stick to the glass, they flow with the current and they can swim, sigsag way of swimming
there is no sign of them attacking my fish but my fish did eat them
what should I do? just leave it or do a 100% water change

They are probably planaria so dont worry too much. Definitly don't do a 100% water change - 30 - 40% should be enough.