Freash water fish dying in tank

Question
Uncle has a large freash water tank with at least 15 fish in it. from last night till now 9 off them have dyed. six more look like they are ready to dye, they swim around fast at first then lay on there sides then just dye. any thing I can look to do to help.   Thanks Rich.

Answer
Hi Richard,
You really should check your water quality. Bad water conditions are the leading cause of fish loss. Especially if this is a new tank, ammonia can build to dangerous concentrations. Try to test your water if you can.

For now do 50% water changes over the next several days. Water changes are the best thing you can do for fish and this should help save them. Always make sure the replacement water is equal in temperature or a bit warmer than your tank and make sure it is dechlorinated every-time.

Make sure your tank is cycled. For more info on cycling, visit this link
http://www.firsttankguide.net/cycle.php

If your tank is already established then something must have gone severely wrong with your tank. Likely overfeeding or some other source of pollution. Make sure you haven't overfed or overstocked your aquarium and try the water changes, they should help!

Best of luck!
Karen~