Large fish and large tank questions

Question

Why do people say oscars and other larger adult fish need large tanks when petstores (petsmart) do not house their fish in large tanks? I swear the local petsmart has had these same two large blue fish FOREVER (they are 25.99) in a very small petstore type fish aqarium. I don't buy the line they sell, because they don't. I use to work at petsmart and the same fish would be in our tanks for months at at a time. .

Answer 1

The pet shops keeps them for months...

Properly cared for the fish will live for maybe 10 years, and in the case of an Oscar grow to over a foot long. Just not going to happen in a 20gal tank

You also dont see the big central filtration systems and automatic water changers those shops have, nothing at all like a small home tank with a HOB filter.

Many pet shop staff have never seen an adult specimens of the fish they sell. A local place is selling Labeo and Bala sharks to people with 20gal tanks. After a year they will have outgrown the tank and die in the cramped conditions, but people thinks this is normal and just buy more.

Ian

Answer 2

The reason is because the company expects that people will buy them and they wont be in those small tanks for a long time, which is wrong. When oscars get larger people are less apt to buy them, as where if they are smaller people want to buy them more.

Answer 3

Petco sucks too.

There is no real tropical fish stores within 25 miles and I live in Orange County, California!

Answer 4

Most large pet stores that sell lots of fish have them housed in a series of tanks that are all filtered by the same, HUGE capacity filter.  When folks talk about the size of a tank needed for fish, it is assuming the tank is a "closed" system, much smaller than the capacity of the whole operation at pet stores.  Size of tank recommendations are used for the general consumer to get the same results the stores do, without the benefit of having a gigantic filter.

And as others have stated, the fish in pet stores are intended to be sold before they get big, even if they don't get sold until they grow much larger.  

Look at it this way - birds and fish have the most wide-ranging habitats in the world (the air, the water).  When we take them home and create a home for them (fish or birds), we are limiting their natural instincts to roam about (fly over the land, swim in the big lakes/oceans).  Why wouldn't you want to provide the largest tank you could afford for them?

And in theory, you could keep a big fish in a tank smaller than what is recommended.  However, you'd end up doing more work keeping the nitrate levels within safe limits by having to do more frequent water changes.  Most people don't keep up with the water changes when needed in smaller tanks, causing chronic poor water quality which can severely limit the growth, health, and longevity of fish.