fish are gasping and laying at the bottom.

Question
Yesterday I did a 40% water change on my 55 gal. tank.  My husband also cleaned out the filters.  We have a charcol carbon filter.  All seemed to go well and the fish were fine all day today until about 11pm I went to feed the fish before bed and my Brown tang and porcupine puffer seem to be gasping for air.  the Puffer will swim to the surface but then just sinks to the bottoms.  The Tang is laying on its side gasping.  What can I do?  what may I have done to do this?  the Nitrite and Nitrate levels are both excellent.  Ph is a tad low, but other than that the water seems fine.  Can I save my tank?  Please help!

Answer
Hi Brenda,

It seems one or more of your water parameters has gotten thrown off, when you did your water change.

My recommendation would be to add some beneficial bacteria, such as bio-zyme or brightwell aquatics microbacter7, this will instantly help to boost your beneficial bacteria in the aquarium, which will help to stabilize your water parameters.

In the future you could try the following:
Instead of doing a once a month 40% water change, try doing two smaller 20% water changes each, per month.

Regarding changing filter media:

Never fully clean out the filters, this is where a lot of the beneficial bacteria grows. Only change the carbon media out and clean out the hose lines.

I wish you the best in all your future saltwater aquarium endeavors.


Regards,
Dave