I continue to see questions like this on yahoo answers about changing the ph of your aquarium.  New fish keepers will attempt to alter the chemistry of their water with whatever potion they find on the fish aisle of their pet store.  The reality is that almost anything you do to change the ph will be worse for the fish than the ph to begin with.

People keep these fish in bowls. This one could eat the bowl.

Please take a moment to check our aquarium store listing has your favorite store.  We are trying to build the largest, most useful list of aquarium stores on the planet! 

This article aims to list some best practices for designing and maintaining filtration systems for freshwater aquariums.  Some or all of these may not apply to a given circumstance or size aquarium.  This article is an extension an improvement of the earlier article on Rena Filstars filters.

Redundancy

I put some duckweed into the 55G tank in my office about 3 weeks ago.  As of late, the tank is nearly overrun by it.  Therei s a thick mat of the stuff covering about 60% of the surface of the water.  I was looking in and saw a swordtail fry.  I looked closer and saw dozens of them hanging out in the duckweed.  Apparently floating plants really are good for raising fry.  Up to now, I had been moving my fry into a breeder net.  I decided to leave them in the duckweed to see how they do.
I am going to try to get pictures tomorrow. 

It's important to understand that in most cases, fish that exhibit symptoms are very ill, and so it is normally important to act quickly.  Nearly every illness can be attributed to one (or more) of 5 things:

Most new fish keepers buy "hang on the back" filters, like the Marineland Penguin series of filter.  Many aquarists eventually move to canister filters for a number of reasons:

I am often asked what fish are good for beginners, and that can be a tough question to answer, since there are a lot of variables like tank size, and whatnot.  Goldfish tend to be the common starter fish, but an understand of the physiology of goldfish will lead you to realize that they are best left for large ponds, in the long run.
 
Below are a list of fish that are commonly available, typically healthy and are robust enough for beginners:

Drip acclimation is typically used when introducing sensitive fish to a new aquarium.  The "drip" of water from the new aquarium allows the fish to slowly adapt to the parameters of its new environment.
Typically, drip acclimation works like this:

Early in my fishkeeping days, after I had killed many a fish due to ignorance about the nitrogen cycle, I was quite frustrated by my inability to keep new fish alive, particularly the more delicate fish like Angels and Rams, but also common fish like dwarf gouramis, mollies and swordtails.  Like most, I was buying my fish from the local Petsmart and Petco's, bringing them home, floating the bag, adding a bit of water, then letting them loose.  Within a few days, the fish would start developing sores or just outright die.