Prazi pro is fine for tapeworm and gill flukes
If you use the medication in the tank each week for 4 weeks, the initial treatment will kill any tapeworms and gill flukes on/ in the fish and in the tank. And the weekly follow up treatments will kill any baby worms or flukes that hatch after the first treatment. At the end of 4 doses the fish should be clean and free of any tapeworm and gill flukes and the only way it will become infected again will be through exposure to contaminated food, fish or plants/ ornaments from contaminated tanks.
Tapeworm and threadworms are most commonly spread by live daphnia and other small crustaceans that come from waterways with water birds. Avoid feeding fish organisms that come from a pond that has ducks, geese, swans, etc living in it, and you should never see tapeworm in your fish again.
Fish in shop tanks are often affected by worms and any new fish should be quarantined for a month before it is added to the main tank. During the quarantine period you should treat any new fish with medication like prazipro and nilverm (for threadworms).
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You will need to find a different medication to treat threadworms because Prazi Pro does not treat those sorts of worms.
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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 the page, and this can convert litres to gallons.
Remove any carbon from the filter before treating the tank. Throw used carbon away.
Increase aeration when using medication.
Do a big 75% water change and complete gravel clean before treating the tank. And wipe the inside of the glass down as well.