Dead Fish =(

Question
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Followup To
Question -
Hello there, on December 13th I decided that my poor fish had been lonely enough,  so I decided to buy 2 more fish at a fish store here. My fish was a goldfish with the eyes that stick out(sorry I don't know the names) and then I bought a black gold fish with the big eyes and a fish that sucks the walls. =) Yesterday, my fish was found floating upside down  in the water. I just figured it was old age, because he was a tad bit old I'm guessing. Then this morning, the 2 other fish were found dead. What could have caused this? They all seemed really happy except for the last couple of days and I noticed my older fish acting a tad bit strange. I'm thinking maybe the other fish might have had a disease. I had them a little less than a month. Anyways, thank you and happy new years!
Answer -
Hi Jessica;

That's a shame. Poor guys......

If you can give me a bit more info maybe we can figure out what happened to them;

What size tank is it?
How big were the fish?
How long was the tank set up?
What kind of filter does it have?
Does it have a heater?
How often do you usually clean it?
How much water do you remove when you clean the tank?
What did they act like before they died?
What kind of food, how often and how much do you usually feed?

Let me know as soon as you can........

Chris Robbins

The tank is 25 gallons. The tank has been set up for about 4 years I'm guessing. My mother had it about 2 years before I got it so I'm not completely sure. The biggest (the first one) fish was about 4 inches long if that. I have no idea what type of filter it has, it was bought at Walmart. Sorry. There was no heater. We cleaned it every 3 months. We took all the water out whenever we cleaned it, but it wasn't cleaned while we had the new fish. The 2 new fish was kind of a surprise of them dying. The old one had been floating kind of in an upward position right next to the filter. At first I thought he was dead but then I opened up the tank and he swam around like it was nothing. He did this for a couple of days and then the next day I found him floating upside down. As for the other two they did nothing, that seemed remotely strange or made me curious they were going to die. I just figured it was the old ones time to go. The fish food is Wardley, it's just goldfish flakes. I would feed them one to two times a day.  

Answer
Hi Jessica;

It was probably too much new fish to add in at one time. The beneficial bacteria balance has to adjust to the new population slowly so only one new fish should be added and then wait a week or so before adding another new one. Some tanks do okay when several are added at a time, but yours doesn't seem to be able to handle it. You didn't mention a filter, does it have one? Or, maybe it's too small? That could be the problem.

Tanks really need water changes more often than every 3 months. The water chemistry changes on the fish so rapidly when a major cleaning is done that many fish don't even survive the stress of it. PH and hardness levels are quite a lot different in new tap water than with 3 month old tank water. Cleaning out the whole thing also destroys the beneficial bacteria that the fish need growing in there so it can consume the fish waste. The tank goes through what is called a "Break-in Period" every time. This is the period of time that the beneficial bacteria is trying to get going. Waste toxins will become very high until the bacteria can take over so it is very stressful to the fish. With only a couple of fish in there alone so long it probably wasn't as bad as it could have been if the tank was fully populated.

The best cleaning regimen to follow is to replace 25% of the water while vacuuming the gravel every week to two weeks. It is much less stress on the fish and less difficult than draining the whole tank too. If you aren't familiar with an aquarium vacuum, visit your local fish store. They should be able to help you with one and how to use it. If you see a lot of crud coming out of the gravel when you vacuum it means you are overfeeding. We all overfeed from time to time, we just have to clean up after ourselves when we do. Feed only once a day or every other day and watch to be sure the fish totally consume all the food everywhere in the tank within 5 to 10 minutes. Even if they eventually finish the food that's leftover they can't fully digest it and it adds to excess waste in the tank.

Goldfish have a life span of 10 or more years, so I doubt it was old age that killed the first one. I really think it was old water chemistry in combination with the toxins from adding new fish. They just couldn't take it.

Followups welcome

At Your Service;
Chris Robbins

Come on over and join us on the freshwater fish forum at About.com to get even more information too;
http://freshaquarium.about.com/od/questionsanswers/a/naavigateforum.htm

My member name is ChrisR62. See You There!