goby died

So I noticed the past day or two my 13.5g saltwater tank start to get a bit of algae growth, I decided to do a water change today and found my goby dead beneath a rock, so I removed it as well as the contaminates, now my clownfish and damsel are breath fast, and my clownfish are laying on the...

I introduced a male to my female a couple of days ago to see if they would pair up. I got a male that was bigger than the female cause I heard that females may kill males that are smaller than her. Well today I found my male dead. His mouth of wide open and he has pale spots spots like he lost...