The basics of keeping fish & where to get more help

You don't keep fish, you keep water.  This is the advice given to me by a wise old fish keeper once.

Although a little perculiar, the advice is sound.  There are a few issues which may plague the fish keeper (with regard to the quality of their water); get these right (it's really not that hard) and the rest certainly becomes a lot easier.

To understand 'water quality' as a concept, you need to first understand what's going into the water.  Fish produce ammonia (NH3) as a part of their bodily waste (poo), this is a highly toxic substance to fish and needs to be processed.  To do this, we require a nitrifying bacteria (these, generally speaking, live in and amonst the 'media' in your filter).

So whether you're looking at a tropical fish, goldfish or Koi carp, the concept is the same; and I'm sorry, but whatever that store told you about not needing a filter for 'that' fish is...well...'ammonia'.

So your filter will (should) handle the ammonia and convert it to nitrite (NO2) and a secondary bacteria will convert it into nitrate (NO3).  We can then change some of the water in our environment to reduce the amount of nitrates in the water.

This is the basic principle to keeping any fish, whether in an aquarium or pond; get this right, and you're away.

Your local fish shop is often a good source of fish keeping information and can help with many queries.  If you're not getting the advice you need, or if you're wanting support from a community of fish keepers, check out http://www.keepingfish.info.  This group is a global community of fish keeping nerds geeks awesome people that can answer pretty much any question with a "I've been there" background.  So you're getting honest advice from people that have been there before; there's a collection of people from very new beginners through to 40+ year fish keepers.