Basics of Freshwater Aquariums
Here is the no non-sense guide of what you need to know to keep freshwater fish.
(Edit: Note - the scope of this article is geared toward a small ~10 gallon or under setup, as we would expect a beginner to have. Recommendations on filtration and processes vary slightly as you advance into larger setups.)
First the part we all know, fish live in water. Glad we got that out of the way! Your fish also "drink" this water, most species breathe dissolved oxygen from this water, and ALL species of fish produce waste. Besides the obvious places, waste also comes from excess uneaten food decomposing. Since your fish live in your aquarium water, it is important to keep it very clean!
Keeping your water clean is a lot more simple than you think, and you need far fewer items than many sources advice. Your waste is removed from the tank through two main processes, and a third optional process that we will discuss at the end.
First is probably the most important thing to understand about aquariums, the nitrogen cycle. Waste is made in the form of ammonia, which is very toxic to all living things, especially fish. Ammonia makes no visible signs, and the only way to reliably detect it in your water is by testing your water. We(like most fish stores) offer water testing as well as sell API's test strips which are very easy to use, and while not as accurate as chemical test kits, they give more than enough information to paint the picture. Ammonia is broken down into nitrites, and then nitrates by bacteria in your fish tank. This bacteria grows on every surface of your tank. Both anaerobic and aerobic (meaning species requiring and not requiring oxygen) are needed for this process, as the bacteria that converts nitrites to nitrates requires oxygen. This is where your aquarium filter comes in!
We always recommend air driven sponge filters, as they last a very long time without replacements, and they offer a lot of surface area filled with bacteria. They also offer all the same benefits to your tank as an air stone. They require only an air pump to operate. The sponge filters are also excellent at mechanical filtration, that is to say removing small particles from your water that tend to make it cloudy. The process of converting ammonia to nitrites and then nitrates by your filter is known as biological filtration. Sponge filters are excellent at both, and in our opinion are one of the best and most economical filters. We stand by this as we use them on every one of our tanks. The only maintenance is to rinse these in your tank water just before a water change, and replace them when the sponges are physically worn. We also recommend the dual sponge filters, and only cleaning one side per water change so as not to disturb all of your beneficial bacteria.
Speaking of water changes, second process at work in keeping your fish healthy, is WATER CHANGES. Nitrates, although less toxic than ammonia, are still toxic to fish in high quantities. Therefore, we change some of our fishes water to dilute the nitrates, but not all of it so as to disrupt the nitrogen cycle and other biological processes (as well as stress your fish). In the aquarium hobby, we measure the levels of these waste products in parts per million. When you perform a water change, you are creating more parts of clean water to make millions out of.
If you follow typical stocking guidelines for fish (and if you have any question on what those are, please ask us!), you should do water changes at a rate of 10-20% of the total volume of your aquarium water once per week as a baseline. As your tank becomes more well cycled (colonized with bacteria), you can decrease or increase the frequency as needed. The only way to tell is to have the ammonia, nitrite, and nitrate levels in your water tested. Most fish stores offer this, including us, and again you can purchase your own test kits. You should look for your numbers to read as close to 0 as possible. Ammonia can spike sometimes for various reasons, so it is important to monitor your levels, and change water immediately if the readings are high. AT NO POINT EVER in the hobby should you change more than 50% of your total water volume, unless something has gone catastrophically wrong. There is no maximum frequency you can perform water changes. Live plants also consume nitrates, and can SUPPLEMENT (or in some extremely rare, very obscure cases, replace), your filtration system. There are many low light, easy aquarium plants to choose from, and these are the only plants we carry.
Water should always be changed with clean non-chlorinated water. You should also avoid using distilled water. If you use chlorinated tap water, a chemical dechlorinator/water conditioner will instantly make your water safe to use. You should also make sure your water is of an appropriate temperature for your species of fish, and with the exception of being clean, as similar to your existing water as possible. Sudden swings in water conditions are very stressful to all species of fish. The slower you can make any change to your aquarium, the better it is for your animals.
Most species of fish also have stomachs the size of their eyes, and overfeeding is VERY common. Although we do not suggest it, fish can go quite a long time without eating with no harm to the animals. In general, for most species, we recommend feeding a high quality food, such as any of the stock we carry, appropriate for your species of fish, once or twice a day, skipping one day per week.
The third optional process we mentioned before is chemical filtration/aquarium chemical additives. Chemical filtration uses carbon, etc in your filter to treat your water. We have a whole different article on chemical treatments, but most of the time, we do not recommend using any chemical treatments or medications. They can disrupt your nitrogen cycle, and cause an ammonia spike, and they typically only treat symptoms, but do not solve the original problem causing the symptoms. Additionally, once you start using carbon in a filtration system, it is difficult to stop without a spike in ammonia. UV sterilizing lights are very similar with the effects they provide, and so we group them in with this line of reasoning as well. The only difference is they sterilize the water through bombarding it with UV radiation(light). The only aquarium chemical treatment we use besides dechlor/water conditioner is methylene blue. We use it in our quarantine tanks in some cases, as well as sometimes when shipping fish. We've discussed the uses of methylene blue in another article.
If you have any questions, please let us know! You can call, text, email, or communicate with us on social media. We're always available for specific questions
We hope this helped you understand the basics of fish keeping, and furthered your understanding of the hobby.
Our sincerest thanks!