Fish compatibility: before buying your first freshwater fishes make sure you know their water requirements and behavior towards other fishes. Don’t buy “nippy” or territorial fishes if in same tank there will be more delicate small fish species that could get nipped or chased out of the territory – remember some species are very aggressive towards others once they grow larger! Compatibility between tropical and coldwater aquatic life forms is also an important factor to consider when mixing them into one aquarium setup.
Now the most important decision – choose your first freshwater aquarium fishes!
Always keep in mind that hobby of keeping fish is very rewarding, yet can also be frustrating – so if you’re not sure about compatibility of some species it’s better to buy only one or two freshwater aquarium fishes and wait till they grow up before adding new ones.
7 Things To Consider Before You Buy Freshwater Fish
Over this last year, my husband and I have learned quite a few things about caring for freshwater fish and I wanted to write a post dedicated to any potential parent who is considering making the purchase. If you are interested in buying freshwater fish, there are a few things you have to know, which will help you in your purchase decision:
Freshwater fish have babies
We started our tank with about 10 fish which is not much considering we had the 65-gallon tank. I think you are able to get one fish per gallon (or something like that) according to “the rules.” We intentionally left them a lot of room to roam to swim. But over this last year, TWO of our freshwater fish had babies. LOTS of babies.
The first lot was eaten by another fish which made my children CRY. The second lot somehow survived and now I have double the amount of fish I started out with! Like I said, we have the room for it, but we have a feeling that over the next few months, things might get a little crowded. Just know this will happen to you.
Types Of Fish To Consider
Some common freshwater fish species:
- Angelfish (Ctenops nobilis) : A beautiful large-sized fish with a lifespan of 15 years. They require larger tanks and are known for being territorial towards other angelfish species unless alloted enough space – they can grow up to 10 inches in size.
- Discus fish (Symphysodon) : a beautiful species of cichlids that needs to live in groups and should be provided with proper setup for breeding – this is one of the most popular freshwater aquarium fishes as they are easy to care for and very colorful, but also might not fit well into smaller setups due to their large size (they can reach up to 8 inches). Discus fish are known for being aggressive towards other fishes when grown larger.
- Betta fish (Betta splendens) or Siamese Fighting Fish : a beautiful tropical fresh water species that has long tail shaped like an arrow, it’s male counterpart is called “farmer fish” as it’s used to fight with other male betta fish. These aggressive one-inch-long fresh water species live in shallow pots or separate tanks, but can be kept together if kept small enough – after reaching 2 inches long male betta might start killing the female one (they are 100% monogamous).
- Swordtail Fish (Xiphophorus hellerii) : a pretty tropical freshwater fish that has a unique sword-shaped tail fin and is very popular among aquatic life hobbyists due to their exceptional behavior of swimming on the surface of the water and jumping out from time to time – they’re easy-to-keep species that grow up to 6 inches in size and require larger tanks.
- Platy Fish (Xiphophorus maculatus) : a popular freshwater aquarium fish that enjoys company of other platy fishes and can live in small groups – it’s known for being hardy and long-living species, but also might nip at plants when grown larger, just like any other similar tropical fish species. They’re easy to care for and are available in a wide range of colors.
- Goldfish or Carassius auratus : A kind of carp native to rivers running from China through Korea and Japan best known as ornamental freshwater aquarium fish having been selectively bred into countless varieties of colors – they’re available today in many color variations: red, blue, yellow, white ones with black stripes and more. Long-living species that can grow up to 10 inches in size, they’re usually kept either alone or in small groups (max 4 goldfish per 1 gallon of water) – remember not to mix coldwater fishes with tropical ones.
- Guppy or Poecilia reticulata : a popular fresh water aquarium fish species that comes in many color varieties – red, yellow, orange-blue etc… it’s often regarded as a “feeder fish” for larger freshwater aquatic life forms, but this doesn’t mean they should be considered less important than other species – after all guppies are very prolific and easy to breed! Happy mating behavior is achieved under conditions approximating their native habitat: brackish water or tepid fresh water. They can grow up to 2 inches in size and live 5 years.
- The tetra (Paracheirodon innesi): a popular fresh water fish that can survive any conditions except for extreme cold ones – they’re usually sold in group boxes, but often fight between themselves ( some species ) so it’s better if you keep them alone or with very similar-looking tetra species . They come in beautiful colors like red, white, black, yellow and green. This is a hardy breed of tropical fresh-water fishes known for their bright colors and friendly mannerism towards tank mates – it’s an easy-to-keep species that can live up to 5 years.
- The molly (Poecilia sphenops): another popular tropical fresh water fish that’s great for beginners – it has a long lifespan of up to 15 years and can grow up to 5 inches in size, eating small crustaceans or insects. It comes in many colors: red, yellow, blue etc… as well as other beautiful varieties like Dalmatian molly (lilac spots on black background), butterfly molly (yellow with orange polkadots) and more.
Talk to a representative about picking out community fish for your tank. While exotic fish species are nice to look at, their fish behavior is more important in the long run. Different fish act differently together.
Use A Reputable Pet Store
The first thing is the place where you buy your fish from – always choose a reputable pet shop or aquatic life hobbyist that treats their fishes well and doesn’t use any chemicals or antibiotics when treating them. Always ask them if they test the water with reputable kits and how often they do it. (Most of the good ones test for oxygen, ammonia, nitrite levels every day.)
You should also try to keep some space between aquarium glass in order to provide enough fresh air for your new friend – there are special slots you can buy at pet shops that allow tank glass walls to be kept apart without using silicon etc… You can also buy this DIY kit which holds tank glass walls apart using suction cups.
Another thing that concerns freshwater fish is the overall quantity of fish you’re planning to get in one container – keep in mind that some aquatic species require more space than others, so you might have to do math and count how many fish there are in 1 gallon or liter of water, if they’re going to be living together and also look into their respective sizes (bigger fish usually live longer).
You have to clean the water every other week
If you purchase a small tank for your freshwater fish, you might be ok with this chore, but we have 65 GALLONS OMG SOMEONE COME AND SMACK ME. My husband has to take out like half of the water each time and refill it with fresh water and it is just a disaster.
We’ve purchased things to make the process easier, but it’s still wet and sloppy and he always ends up mumbling through in total annoyance. This is one chore he literally HATES. We have joked that we are “this close” to hiring a service to come and do it for us. Although, I’m not so sure he is joking???

The size of the tank matters
If you want to buy fish, get a small tank that is portable. Something you can bring over to the kitchen sink when you need to clean it out! Otherwise, things can get very messy and very expensive. Sure, I got a great deal on Black Friday, but was it really worth it in the end?
I had to buy about 20 bags of rocks and a ton of accessories for the inside of the tank. I had to buy a heater, an oxygen maker, a filter…. we were $700 in by the time we were all said and done. What a mistake! If I had to do it over, I would get a small tank that I can lift and bring over to the sink and that doesn’t require all the extra nonsense.
Vacations become an issue
If you have a dog or a cat, you can just send them over to Grandma’s house while you are away. However, what do you do with a 65-gallon freshwater fish tank? You need to have someone come to your house every single day while you are away. And typically, my husband and I go away for about 7-10 days.
That is really putting someone OUT for a long time. You better have a great payback in mind. Think wine, chocolate, lotto tickets – SOMETHING! It’s annoying and my cousin probably HATES me because she has her own things to do. But the fish will die if you don’t feed them! You have to figure this out.
The Products You Need To Set Up Your Aquarium
A freshwater aquarium setup is fairly simple, it’s even easier if you live in an apartment since you can buy a beginner kit that comes with everything you need: the fish tank, air pump, heater and everything else needed to start your aquatic hobby.
You should be aware of some important things concerning how long freshwater fish can live in one container – for example certain species/varieties have been known to get depressed or develop diseases if they’re kept together in too small numbers. So it’s always better to go for bigger containers when choosing your fish.
Keep in mind that most tropical freshwater fishes need warm water for optimal living conditions. Also, keep an eye on your aquarium’s water levels and never let the fish have to live in dirty water – change it regularly by siphoning it with a gravel cleaner / filter.
Temperature should be monitored daily, especially during the summer since many tropical fishes cannot handle higher temperatures – some species will die quicker than others would if they’re kept in warm tanks where water temperature goes above 86 degrees F. Many fish that belong to temperate waters require much more care and a cool environment – you can’t just stick them into warmer habitats without looking for ways of cooling down their tank or setting up other measures like that. Also, remember that certain aquatic creatures simply prefer cooler conditions so try not to overheat their environments if possible (hint: remove the heater or don’t use it).
Some fishes can survive in cooler conditions while others thrive in warmer ones – the thing is to try and make them as comfortable as possible! A thermometer will help you monitor water temperatures at all times, so always have one by your side. As a rule of thumb tropical fish should be kept away from thermometers that go above 86 degrees F. You should put ice packs on top of them if their temperature becomes too high.
Experienced beginner aquarists usually give their freshwater fish tank an average water change once every ten days – but beginners should do it every 5-7 days (this depends on the types of species you choose when choosing freshwater fish for beginners). Don’t forget to clean your filter and gravel every time you do a water change.
You should always sterilize your aquarium’s equipment with bleach, make sure to wear gloves when handling the tank or cleaning solution – this is extremely important since most tropical freshwater fish are very sensitive – they can easily develop diseases if exposed to bacteria (remember that getting into contact with certain chemicals and products can be fatal for them – take proper care). You should clean any product before use – make sure there are no leftover unpleasant smells in it: your fish will thank you for it!
The kids eventually stop caring
I know. You probably think that your children are 100% invested in these future freshwater fish, right? They just look SO EXCITED RIGHT NOW. It ends after three days. Make no mistake. The only person who will continue to care about the fish will be YOU and it will mostly revolve around the fact that you HAVE TO in order to justify the expense.

Freshwater fish require levels testing:
It’s not just the water cleaning that you have to worry about. You also have to put things into the water to make sure the levels are neutralized. My husband takes care of this and honestly, I can’t say much more about it. All I know is there are dipsticks and liquids and droplets that you have to deal with when caring for freshwater fish. I have three kids! I can’t handle much more.
If I didn’t convince you by now to get a small tank, I don’t know what will. Leave the big tanks to the restaurants and the doctors’ offices. You don’t need that kind of hassle in your life.
Do you have freshwater fish? What kind of tank do you own? Does your family still care about the purchase? Or has everyone simply forgotten! Would love to hear whether or not I am alone on this one.