Eric is an aquarium enthusiast with over two decades of experience caring for a wide array of tropical fish.
How to Care for a Freshwater Tropical Aquarium
Keeping a tropical aquarium can be a rewarding experience. Freshwater fish tanks are inexpensive to set up and maintain, and there is an incredible array of fish available with which you can stock your new aquarium.
Building a tiny ecosystem of animals and plants is an amazing feeling. Many people are hooked for life after they purchase their first fish tank, and their hobby quickly expands to bigger aquariums, more aquariums, or both!
Unfortunately, for many fish keepers, it can also be a very bumpy road. Understanding which fish to purchase, what basic maintenance to perform and when, how much and how often to feed among other details is important for keeping your fish alive and healthy.
For beginners, it can be especially frustrating. There is a ton of information available on the internet, but much of it confusing and contradictory. How is the newbie supposed to know where to start?
In this article, you will read about 6 tips that, if followed, will greatly increase your chance of success as a newbie fish keeper.
If you keep at this aquarium thing it will get easier, and you’ll be a pro one day. But since you probably don’t wish to leave a trail of dead fish in your wake as you plod forward and learn the ropes, it’s worth it to get a few basic ideas down.
Poor tank maintenance is one of the biggest reasons tropical fish die too soon. Here are 6 things you can do to increase your chances of having happy, healthy fish, and a great-looking aquarium.
1. Cycle the Tank Before Adding Fish
In case you’ve never heard the expression before, “cycling a tank” means to take the steps necessary to bring the water conditions up to where they are healthy for the fish. This is something that should be done before you ever add fish to your tank. In other words: You should not purchase your fish tank and your fish on the same day!
Cycling involves the growth of healthy micro-organisms within the tank, which will break down waste and help keep the water safe for fish. This takes a little time, and most experts recommend letting the tank run for at least a week before adding fish.
It is important to start a new aquarium the right way. Many new aquarium kits come with a little packet you can use to add the necessary elements for cycling, or you can purchase it separately at the pet store. You can also cycle the tank simply by adding a little fish food, which will begin to break down and kick off the process.
What you should never do is attempt to cycle your tank with fish already in it. This is very unhealthy for the fish, and until the water parameters are safe they can easily become ill and die. It’s the equivalent of a person trying to live in an atmosphere of noxious gas, and not very kind to your fish.
2. Test and Monitor Water Parameters
So how do you know when the water is safe for your fish? It’s smart to purchase an inexpensive water testing kit and monitor the levels of ammonia, nitrates, nitrites and the pH of your water. I recommend the API Master Test Kit. This is the testing kit I've used over the years. It's easy to manage and the results are very clear. If you test the water weekly, one kit should last you quite a while.
Ammonia, nitrates, and nitrites are natural chemical compounds that result from the lifecycles in your tank. They are fine at low levels but left unchecked they can build up to unhealthy amounts. Follow the instructions on the test kit and take the necessary steps to keep the water parameters correct.
You can also test the pH of your water source with the kit. Most fish can adapt to most pH levels, but if the water is very hard unfortunately it may be necessary to bring the pH down with chemicals.
3. Perform Regular Water Changes
If you find your water parameters out of line there are over-the-counter products that will help keep these chemical levels in order. But, in my opinion, clean water is usually a better answer than adding even more foreign chemicals to the tank.
Frequent water changes are the key. You need to remove about one-third of the water from your tank every week and replace it with fresh, clean water. This dilutes the chemicals in the water and makes it healthier for your fish.
If fact, if you fail to do this you will find your water parameters harder to keep under control. The waste buildup will pollute the water to the point where it becomes unhealthy for the fish.
You should also learn to vacuum the gravel in your tank, to remove the debris that has accumulated on the bottom. None of this has to be hard, and it doesn't take more than a few minutes of work every week. Water changers and siphons are available, which enable you to vacuum and remove water at the same time.
4. Research Fish Before Purchasing
When it comes time to purchase fish, take some time to research exactly what you are buying. Understand how big the fish will get, its temperament, its space requirements and which fish it will get along with.
It’s a beginner’s mistake to go to the pet store and purchase fish by looks alone. The attendant at the pet store should be able to set you straight, but unfortunately, they often aren’t very knowledgeable themselves. You could end up with aggressive fish species without realizing it, or fish that simply aren't compatible.
Better to do your own research and learn about your pet before purchase. You’d do that if you were buying a dog, right?
Along these lines, do not overstock your tank. You may have heard the “one inch of fish per gallon” rule. This advice is nonsense, and you should ignore it. Knowing what fish you are purchasing and their needs help you to understand how many fish can safely live in your tank.
An overcrowded tank results in increased aggression, increased stress, increased disease and an overall unhealthy living situation for your fish. It is far better to under-stock your tank and have fewer but healthier fish.
5. Avoid Overfeeding Your Fish
Rest assured, it is very difficult to starve a fish. One feeding per day is plenty, making sure you provide food items for each type of fish in your tank.
A good flake food meets most needs, but if you have many bottom-feeders you may wish to include sinking pellets. Don't assume catfish and other scavengers will get what they need from flakes that float to the bottom of the tank. If you have algae-eating fish in your tank you'll want to include algae wafers to supplement their diets.
Do not feed more than the fish will eat in a few minutes. Excess food is not only unhealthy for the fish and can lead to disease, but it dirties the tank and can cause spikes in the aforementioned chemicals. It can also help cause undesirable situations like excess algae growth or an outbreak of pest snails.
Many fish keepers put their fish on a feed/fast schedule, utilizing one or more days per week when the fish are not fed. This helps to keep the tank cleaner, and the fish healthier. In simple terms, remember that what goes into a fish must come out, so the more you feed your fish the dirtier the tank will get.
6. Manage Light in and Around Your Aquarium
One of the most frustrating things for the new aquarium owner is managing algae in an aquarium. Algae are similar to plants, and like all plants, they require light to thrive. Of course, you are going to have lights in your tank, because you want to see your fish. So how do you see your fish without growing a huge crop of algae?
One way is to manage the amount of light your tank gets every day. When you decide on the placement of your tank, try to keep it away from anywhere that will get strong sunlight throughout the day. Like any plant, algae loves sunlight and will flourish if given the chance.
You should keep the tank light on a maximum of 12 hours every day. In reality, you can probably do with much less. Remember that the light in the fish tank is for you, not the fish. The moderate lighting of daylight is plenty for them, and about what they would experience in the wild. If there is nobody home there is no point in having the light on. You can keep the light off while you are work or at school, and turn it on when you come home at night.
Obviously the exception here is if you have live plants in your tank. They will, of course, require a full 12 hours of overhead lighting per day. However, live plants will suck up many of the nutrients algae needs for survival, and in themselves can keep algae levels in check.
Learn As You Go
It all may seem daunting, but if you incorporate these tips into your fish care routine you’ll end up with a pretty tank full of healthy fish. Once your tank is up and running the care and maintenance required to keep it going really should not take up a lot of your time. As little as an hour a week is all that’s needed, maybe less depending on tank size.
Remember that fish are not disposable pets, and if you choose to keep them in your home they are worth taking the time to care for properly. Like any animal, your tropical fish need a clean, safe and stress-free living environment. It’s up to you to make that possible, and it’s not as hard as it seems.
Yes, you will make mistakes and lose a few fish along the way, and everyone does. But as long as you are doing your best you shouldn’t feel bad about it. We’ve all been there.
Good luck with your tropical freshwater aquarium!
Questions & Answers
Question: How often should I replace the inserts in an aquarium filter?
Answer: It depends on what kind of inserts you are talking about. There are three types of filter media commonly used in aquariums: Mechanical, biological and chemical.
Mechanical inserts merely trap debris in your filter. This could be a sponge, foam block or something similar. I don’t like to replace these unless they are starting to disintegrate. You do want to take it out once a month, rinse it out and remove any debris trapped in the filter itself.
Chemical media is intended to alter water conditions in a positive way. Activated carbon is common, but there are others. Follow the manufacturer’s recommendations for advice on when to replace them.
When we talk about biological filtration, we mean the colony of helpful bacteria that live in your tank. These microbes break down waste chemicals, making the water healthier for your fish. They live all over your tank, but especially in your filter and gravel.
We can help them out by adding biological media to the filter. This is usually a mesh bag with a bunch of pellets inside, which gives the microbes more surfaces on which to grow. As with the sponge, you can rinse off any gunk when you clean your tank, but you don’t ever want to replace biological filter media unless it is falling apart.
So, what about those filters with the all-in-one inserts that do everything? You’ll want to check with the manufacturer for their advice on when to change them out. Because they usually have carbon in them, the typical recommendation is to change them every month. Just remember, when you toss out the cartridge, you are tossing out a lot of your helpful bacteria.
As for me, I wouldn’t change it unless it was disintegrating. I’d rather have the bacteria than new carbon.
Question: What size tank should I get for guppies?
Answer: You’ll need a 10-gallon aquarium, minimum. Guppies should be kept in a school of six or more, and you should shoot for one male for every two females. That means you’ll be choosing your number of fish, and your tank size, by the interval of three. In other words, you can have six, nine, twelve or fifteen guppies, but not seven or ten or eleven. Keep in mind this is a suggested best practice. Things go off the rails quickly with these little guys, so don’t stress yourself out if your ratio is a little off.
Guppies are also one of the few fish where the “one-inch-per-gallon rule” applies. I generally tell people to disregard this oft-repeated rule of thumb, as it doesn’t make much sense for most fish species. However, guppies are little fish with a low bio-load, and they are around an inch long. So, we can use this “rule” to decide on tank size.
Putting all of this together, say you decide you want 15 guppies. You will need at least a 15-gallon tank. If you want 30 guppies (!) you will need a 30-gallon tank. If you only want a small school of six, again I’d go with a minimum of 10 gallons.
Guppies are also live-bearers and prolific breeders, so you may want to over-estimate on tank size a little, as it may not be long until you see little guppies puttering around. This is the reason you shoot for that 2:1 female-to-male ration. Male guppies tend to get a little annoying, so having more females means the stress is spread around a little more.
Question: What size aquarium is good for a beginner?
Answer: Beginners interested in having a real aquarium with a small community of fish should start with a 10-gallon tank. There are kits available that contain everything you need to get started, minus the gravel, decorations, and fish, of course.
I believe 10-gallon tanks are good for beginners because their small size makes them easily manageable. At the same time, they are large enough to accommodate a proper filter and heater, and even some live plants. Beginners can keep a small number of community fish and learn how to care for them in a real aquarium.
This just isn’t possible with very small tanks. They often come with sub-par filters, and it is difficult to heat them. And, most fish species should not be kept in tanks under 10 gallons. This can lead to failure and frustration for the new fish keeper, and cause them to quit.
If a 10-gallon tank is out of the questions, consider a 5-gallon tank with a single betta fish. This will get you started, and you can move up from there.
Of course, there is nothing wrong with going larger if you have space. A 55-gallon tank may seem daunting, but the same principles apply as with a 10-gallon. And, because they are larger, they are a little easier to care for.
Eric Dockett (author) from USA on June 27, 2020:
This is a response to a question from Larry P. You included your email in your comment and I didn't want to publish that for the sake of your own privacy. :-)
The first thing I might try is switching to monthly cleanings rather than every two weeks. You can do a partial water change every two weeks if you want, but actually cleaning surfaces and/or filter element too often could be causing bacterial blooms. It's hard to say.
Here is an article with more info on cloudy tanks:
Eric Dockett (author) from USA on February 21, 2020:
@Rose - The algae itself wont kill the fish but your tank is seriously overstocked, which can lead to conditions that promote algae growth.
rose on February 20, 2020:
I have a 10 gallon with 6 gold fish. Just noticed algae growth on back wall -brushed it off. Will it kill the fish, as it disintegrated into the water. Thanks-
Eric Dockett (author) from USA on September 06, 2019:
@Norma - Could be algae or even fungus, but I would only be guessing without seeing it. Maybe take a sample to a local fish store and see if they can identify it.
Norma Baker on September 04, 2019:
We have a grayish substance that not only does it float in the water but will accumilate on the bottom of the tank forming large clumps. It is a sixty gal.tank with tetras(10), multiple plecos due to a breeding pair, cory(1). Is it due to overfeeding?
Eric Dockett (author) from USA on July 31, 2019:
@Pat - Unfortunately there is no way I can answer that question without more information such as number of fish, their size, water parameters, etc.
Pat on July 30, 2019:
I have a 60 gallon tank and I had a few gold fish but they all have died .I was feeding them once a day and keeping the tank clean, but they still died . what am I doing wrong?
Jovonie Salas on September 15, 2018:
I have a 30 gallon tank with 13 different species and they all get along just fine especially my gold fish I had for 6 years never tried eating my smaller fish
Eric Dockett (author) from USA on March 11, 2018:
@Dorothy - What's kind of cichlid is it? He's been hanging in there for four years so you must be doing something right. The same general rules for tank care that apply to other tropical fish also apply to cichlids. He will eat cichlid pellets, and depending on what type of fish he is you may want to consider live foods like feeder goldfish. It sounds like your tank is big enough for him, as long as he is in there alone. If you add more fish you will need to do some research to ensure compatibility and probably upgrade your tank. But as it stands I'd just worry about general tropical fish tank maintenance.
Dorothy Leezer on March 11, 2018:
I had a chiclid given to me and we don't have any know-how to keep the fish. We have managed for about four years and it is still alive but I can't find any stores that can tell me what to do. Itis beautiful and it seems to understand what we say and when we come to the tank etc: It is about ten inches long. in a 45 gallon tank
arambula on September 01, 2017:
Nice, I was leaving lights on always. I had an algae problem, I added too much algae control liquid, I killed all my guppy fish. (Around 100) . Lesson learned.
Eric Dockett (author) from USA on May 11, 2017:
Hi Tonya. Lesson learned the hard way. :-( Just use warm water to clean the tank. Make sure any buckets, cloths and other paraphernalia are used only for the aquarium. If you need a coarse scrubbing medium to get gunk off you can use some aquarium salt, but make sure you rinse everything out afterward.
tonya on May 09, 2017:
I'm trying to set up a tank for my boyfriend. I killed his new fish we got by getting dish soap in the tank by using a sponge. I did not know this could happen. I'm trying to learn how to safely clean the tank. I'm a little confussed on what to use. pls help
Eric Dockett (author) from USA on May 07, 2017:
@Decent: It sounds like your fish has a fungal infection. Clean water and low stress are as usual the best treatments. If its really bad there over-the-counter anti-fungal treatments you can try. Good luck!
Decent on May 06, 2017:
What's happening with my scat fish. It's growing some white fluffy looking Mohawk. At first I thought another scat bullied and bit it's nose. Since I removed the agrees dive one.
Please help diagnose the problem
Eric Dockett (author) from USA on March 29, 2017:
@sanjok: Not sure what you mean by "sweaper fish". Do you mean algae eaters like a pleco? If so, no, you should not put them in a pond. Unless you live in the the appropriate climate, the pleco may not survive. Also, if the pond has access to a creek or stream you may accidentally release a foreign species into a local ecosystem. This is not only irresponsible, but illegal in most places. Plecos belong in very large aquariums, or in their natural habitats in South America,
sanjok on March 29, 2017:
How much does a sweaper fish can eat or Can it survive in my home made outdoor pool? Will it die somehow?
And lastly if so,in what amount of sweapers i must put in a pool ?
Eric Dockett (author) from USA on July 19, 2013:
Thanks Sheila! I hope people find it helpful.
sheilamyers on July 18, 2013:
Great hub! I know you answered all of the questions I had for the lady at PetCo when I first got my tank. This hub will help a lot of people who are just starting out.