Your First Fish Tank

Purpose of this page

The goal of this page is to provide as much useful information as it can to those thinking of starting out in the hobby or those that are just beginning. Please be aware, the information on this page is not all encompassing, a hobby should be enjoyable and being bombarded with information will more likely discourage you from an amazing hobby.

First and foremost, the most important thing when starting out is to ensure that your fish will survive. To survive, they require a few basic elements:

  • Proper water conditions - If you plan to keep any type of tropical fish such as guppies or neon tetras, you will probably need a heater. Also, make sure to dechlorinate your water.
  • Seeded filter - When setting up your filter, make sure you get some substrate or a piece of the fish store's filter to place in your filter. This is because their filter will have the beneficial bacteria your fish tank needs to survive the nitrogen cycle. Check out the filtration section for more information.
  • Proper technique to introduce your new fish into your tank - Don't just throw your new fish into your tank. Let the bag float on your water for 15 minutes to ensure that the fish are adjusted to your water temperature. Pour the fish out into a net and place them into your tank. Try to minimize external water from entering your tank as it may contain pathogens.
  • Check the tank stocking calculator! Biggest newbie mistake is overstocking your tank! I'm sure you don't want to watch your hard earned money being flushed down the toilet in the form of dead fish.
  • Don't overfeed - Fish don't have to eat a lot to survive. Overfeeding is more likely to kill them than under feeding.

Alright, now that's all out of the way, if you want more information on any aspect of fish keeping, feel free to check out the rest of this page!

Image of a 75 gallon aquascaped aquarium with a sand substrate
Jackson's 75 gallon aquascaped aquarium with a sand substrate

Buying a fish tank


The most important aspect of a fish tank is its size. For a beginner it is recommended that you purchase the largest size that you can afford and that your space can hold. The main reason for this is because a large fish tank is going to hold more water. More water will allow for greater dilution of fish waste and will require less water changes.

For example, if you have a 10 gallon tank stocked with 10 neon tetras, the waste those 10 neon tetras is going to produce is only diluted by 10 gallons of water. Where as, if the 10 neon tetras are in a 40 gallon tank, that is 40 gallons of water diluting its waste, or the waste is going to be four times more diluted in the 40 gallon than the 10 gallon.

A larger tank is going to provide you more leeway with water changes and new tank syndrome when compared to smaller tanks. It will also allow you to purchase more fish for your tank, because that's one of the most exciting parts of the hobby. This is not to say you won't overstock your tank if you buy a larger tank, but it will likely help keep your fish alive compared to a small five or ten gallon fish tank.

Buying used aquariums and accessories

Often times you are going to be able to find some great deals on used tanks online. Especially in the summer time when people are not indoors as much they tend to get rid of their fish tanks. This is a great way to get into the hobby, but you have to be careful!

You want to make sure the tank has no chips. I learned this the hard way when I purchased this beautiful cube tank with a small chip on one side. "It works great, the chip has never been a problem," said the seller. I took the bait hook, line, and sinker. Took the tank home and set it up as an aquascape, looked amazing. Let it cycle for three weeks, because it was using an ADA substrate that released ammonia. Finally, put a dozen ember tetras and a mix of 40 cherry red shrimp and crystal red shrimp in, and left on our honeymoon. Returned a week later to find the tank had busted open where the chip had been. Was absolutely devastated. Moral of the story, don't be dumb like me, don't buy chipped fish tanks.

Re-siliconing a used tank

When I re-entered the hobby six years ago, it was on a whim as we were walking our dog Ollie past a garage sale. There was this old 20 gallon tank with an old aquaclear filter, a heater, a light and some colorful rock substrate for $20. I thought it was perfect, because Anne had talked about wanting to keep some fish, so we scooped up the set. Guess what? The tank leaked, light flickered, and I got rid of the substrate immediately. I've never been the biggest fan of substrate but we'll get to that in the substrate section.

I recommend if you buy a used tank, if it looks pretty old, take the time to remove the old silicone and to re-seal it. Thankfully, it's not too difficult to re-silicone a tank with some time and elbow grease. You'll need the following:

1) A razor blade scrapper (Find these at a hardware store)
2) Rubbing alcohol and paper towels to clean the glass
3) Masking tape or blue painters tape
4) Silicone 1 from the hardware store - Make sure the tube isn't mildew resistant

The following is a great  video that shows you exactly what needs to be done. (Please note: I am not the author of this video and am not affiliated with this YouTube account in any way)


Nitrogen cycle

Please refer to my aquarium filters page for a detailed explanation of the nitrogen cycle. Summary of the nitrogen cycle: fish waste produces ammonia. Ammonia is toxic to the fish and the bacteria in your filter will break down that ammonia into Nitrites. Again Nitrites are toxic to the fish and require a different strain of bacteria to break it down into Nitrates which can be removed from the water with plants, or special bacteria, or by water changes.

Ammonia ----> Nitrites ----> Nitrates ----> Water changes/plants/bacteria

When starting a new tank, get a few pieces of substrate or a piece of their filter media. They should gladly provide you with some as it is in their best interest that you succeed in this hobby and keep shopping there. This media will have some of the beneficial bacteria your tank needs to take care of ammonia and nitrites. Place this media in your filter to kick start your bacteria colony. Make sure the water is de-chlorinated before you do so, or the bacteria will die.

Photo of the nitrogen cycle in an aquarium
An illustration of the aquarium nitrogen cycle



Tap water is fine, just make sure to use a dechlorinator before you put your fish in. I personally use Seachem Prime. Other thing is, when doing water changes make sure the temperature is somewhat close to the normal tank temperature or this could stress or even kill your fish.


If you have to heat your water, make sure your water is heated to the correct temperature before putting your fish in. I think most heaters are pretty dependable. I currently use eheim heaters because I found them at a great price. When choosing a heater, you want to find one with good reviews regarding its internal thermometer, because one with a bad internal thermometer could overheat your tank or cause it to be cooler than your intended temperature.


The type of light you get is not too important for a regular fish tank. If you're making an aquascape tank with plants, then you'll probably want a stronger light depending on whether you use CO2 or not. That is beyond the scope of this article, the only thing I'll say about lighting is you'll be able to see your fish better with a brighter light but a brighter light may lead to more algae. And also, try to keep your light on a timer. Keep your fish's day/night cycle consistent. Last thing, some lights come with a blue light option to replicate light in the evenings which is kind of cool. Sometimes I like to sneak into the room and just observe the aquarium in this light.

This is what great aquarium lighting can do :)
This is what great aquarium lighting can do 🙂


When stocking your tank, take the time to research the type of fish you want to keep. Information you want to focus on:

  • Their ideal temperature
  • Max size
  • Good tank mates
  • Their aggression level
  • Their diets (Some fish are exclusively algae or plant eaters. Others are carnivores)
  • If you're interested in breeding, how to breed and how many of each sex is recommended

Figure out how many of each type of fish you want and then go to the aquarium stocking calculator to figure if your aquarium can handle the stock.

The stocking calculator is not perfect, but it'll give you a good ballpark of whether you're overstocked or if your fish selection is okay.

When you get your new fish

When you bring your fish home, don't just empty the bag into your tank. You'll want to perform a few things first.

  • Turn off the aquarium lights and leave them off for the rest of the day. Aquarium lights are going to stress your fish out and its less stressful for them in a darker environment.
  • First, let the bag the fish are in float in your tank water. The purpose of this is to make sure the fish are used to the temperature in your tank.
  • Next, place a net over a bucket that is going to catch the water from the bag
  • Pour the bag into the net so the fish are caught in the net but the water will flow through into the bucket
  • Place the fish into the tank

Water in the bag is going to be higher in ammonia from the fish being transported and the water may have pathogens that you really don't want to be introducing into your tank. Once the fish are in, leave them be. Don't feed them during that day, you can feed them the following day. If you just got the fish from a long shipping journey, you could try to feed them a little bit of food, but stop immediately if they are not eating it.


Thanks for checking out this page and website. If you can think of anyone that may benefit from the information on this page, please let them know about the page or share on social media. Thanks again!