I have often times seen a large oranda or ryukin swimming alone in a tank of tropical fish at the local petstores. Does anyone know why this is or what purpose it serves. Not only do they look lonely/miserable, but a lot of times the seem to have healthy issues such as swim bladder problems, torn fins or missing scales. Has anyone else withness this?

Many fish stores - the larger chain stores around here - place goldfish into the tropical tanks.

They run a single water system. All the water for all the tanks is filtered from one large filter/pump in the back room. For all intents and purposes the individual tanks are not. The fish are really all swimming in the same big aquarium. The total water volume of the whole system is really the water volume that the fish are using, so if they are in smaller tanks of water, they are still getting the benefits of the larger volume of filtered water.

In doing this, the water parameters of heat, salt, pH, etc. are all the same be it tropical or goldfish. From what I understand most stores seem to keep the parameters a bit closer to tropical needs than the goldfish needs. Most healthy goldfish do quite well with this - they are typically fairly hearty fish. But that is why they can share a tank with the tropicals - the water is the same no matter where they are anyway.

The fish stores will drop a nice larger goldie into all the various tanks in the system, regardless as to what fish are in that tank to make use of the goldfish's procivity for eating snails. The pest snail population in fish store tanks can bloom into the thousands very quickly. The goldfish will eat the majority of snails in a tank.

The down side to running a system like this is that if one fish is sick, every single fish in the system is exposed. And the parameters, not being ideal for some fish, make it difficult for them to stay healthy, once exposed to a problem.

You know alot about fish, dayrl. I always wondered why some petstores did that. Thank you

I did too

Yeah, i;ve always wondered that also! Thanks for having the brain compacticy I lack Daryl!

thanx Daryl, I am glad someone knows about it. I just thought it was cruel punishment to wonderful fish that they dont seem to want to sell. Would be nice if they had a section special for the goldfish so they it would be just them.

that raises another question...with all the water being filtered from one large filter/pump in the back room...I have seen at some pets stores fish that they can not sell cause they are "under observation"...would that mean they all the fish should be under observation?

And what about the feeders....a lot of them have health issues that could be passed on ot the community...

Which raises the importance of quarineing fish before addding them into the main tank

Depending on the store and the method of setup, there can be multiple systems. Feeder fish are typically kept in a large tank that has little or no filtration or even, on occasion, circulation, in many stores I see. They are not hooked into the system at all. Some stores do have a few tanks or part of the set up where fish are not in the system, but in a different collection of tanks that share a filter and pump - it is entirely possible that if you have a store that is conciencious enough to bother to observe and wait on selling a fish then they also are smart enough to keep them in separate waters.

The set ups vary widely from store to store. In one of our major pet stores, all the fresh water tanks are joined as are all the salt water tanks. There are "iso" tanks in the back that are not part of the "system" and fish that are deemed "salvagable" are kept there at times. It really kind of depends on what catches the eye of the person who is in charge of the dept. at the time. The other major store has no facilities to quarantine anything!

You have to realize that, from store to store, even in a chain store, conditions vary so widely that you really have to look at each one and how they are run. Some, I am sure are real hotbeds of contamination. Others probably do a fairly good job of keeping things healthy and under control.

good point there daryl, I see I have some question to ask when I go there next time.