Here are some basic husbandry rules that I use: -
WATER
Remember 'Clear water' doesn't mean fish will live in it, Vodka’s clear, but fish won't live in it!
Buy test kits, (pH, Nitrate, Nitrite, Ammonia & Gh); the LFS are not usually open at night and it is cheaper in the long run. . There are plenty to chose from, individually, master kits and all-in-one test strips. Test your tap water. Then; Leave a cup of tap water for 24 hrs, and then test it again. As well as knowing the chemistry of what you are starting with Sometimes the pH may drop, as certain additives that water companies put in their water to 'buffer' the pH to neutral, deteriorate; if this happens you know that this could effect the pH in the aquarium a day or so after you carry out water changes. Also sometimes the water supply in my area has on occasion proved to contain high level of both Nitrates & Nitrites. All these things can and will cause problems to your fish, armed with this knowledge corrective measures can be taken; if the need arises.
SUBSTRATE
No matter what type of filtration is used, a substrate should be used that is free from sharp edges. If a substrate contains pieces with sharp edges, it is more than likely, catfish that tend to 'root' in the substrate will damage their barbels and secondary infection to the barbels can occur; leaving you with un-healthy fish.
FISH SELECTION
When selecting your fish make sure that all fish in the tank are in a healthy condition, if in doubt don't buy! Make sure the fish you are buying, are: -
(a) compatible to keep with your other fish,
(b) does not have the potential to out grow your tank, unless you really DO intend to buy a larger aquarium when the need arises.
DECOR
Quite a few catfishes prefer places to 'retire' to. So suitable decor like a cave or a piece of aquarium wood, or even a dense thicket of plants, should be provided. As these places make the catfish feel secure in its environment and therefore helping to reduce unwanted stress.
FEEDING
Some people are under the assumption that bottom feeding fish eat what the other fish leave. Although it can be said for some species that this is the case, a lot of "bottom" dwelling fish have their own particular dietary demands which need to be met, for example it is true to say that some species of Loricariidae (pleco's etc) 'eat' bog wood , and that Erethistidae species from Asia prefer a diet of small aquatic invertebrates, therefore these needs have to be met in order to keep the fish healthy. When I purchase fish(s) that I have never kept before, I make sure that one of the first things I do is to find out what the fish feeds on in its natural habitat. Some Local fish stores are good at providing such information, whilst others are not so good, as in the case of pleco's, just because they have a 'sucker' like mouth does not mean they ALL will eat vegetable matter and keep the sides of the tank algae free.