Goldfish died, should I cycle again?

Question
Hello, and thanks for your help.
We have had a 7 gallon hex tank set up since Nov 06, and had one goldfish, about 1.5 inches long. The tank has a built in filter and light. We haven't tested the water for pH, ammonia, nitrates. I changed the water weekly, about 50%, and if the fish was looking sluggish, then an additional 10% change 1-2x/week. The tank had cycled, first brown algae, then green, and became easier to keep clean. We have had this fish since March 07 or so. He died last week, and I am not sure exactly why - no spots, fins in good shape, didn't seem to be dropsy ( he was a goldfish that had a big tummy, but i looked normal to me). My son dropped a plastic painted little fish into the tank, and I didn't realize that for about a week, I think. At the same time, the filter wasn't placed in completely, so it wasn't having the water run across it as it should have. I noticed the algae died, and the water was perfectly clear. I removed the plastic fish, did a 60% water change ( I always leave the water for changes out overnight, and add a touch of the AmQual+), and then 10% daily thereafter. The fish just got worse and worse...my questions are: should I leave the water that's there and wait for algae to return, then get another fish? OR start over completely? Is the 7 gallon hex not enough surface area for the goldfish? Should we have had a bubbler thing? Thank you so much for your help. Sarah

Answer
Hi Sarah;

It probably doesn't need to go through the break-in period again but it wouldn't be a bad idea to change out all the water since you don't know what may have been on the toy. Don't rinse the gravel or anything, just change all the water. Monitor the ammonia and nitrite levels when you get new fish just to be sure things don't get out of hand. You can get test kits at the local fish store and do them yourself. Much easier than having the store do it because it needs to be done daily for a while. The filter failure may have killed off too much of the beneficial bacteria and toxins rose.

It is pretty small for a goldfish, especially if it is taller and the filter isn't strong enough. Goldfish really need a minimum of a 10 gallon rectangular tank and a good strong filter. Your water change schedule is great (weekly changes) but try not to replace more than 25% at a time so it doesn't shock them. You might consider different types of fish such as zebra danios, white clouds, cory cats, ghost glass shrimp. They are all small enough to live in a 7 gallon. Basically, look for fish that don't get larger than about an inch long. Get just two little fish and test the water daily and see how it goes.

I hope all goes well...

At Your Service;
Chris Robbins