40 Gallon Breeder Tank – All You Need to Know

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If you’ve decided to breed your fish, consider the following:

  1. Most fish require special environmental conditions to get in the mood
  2. Most fish have no parental instincts, so they tend to eat their eggs and fry
  3. Those who do have parental instincts become more aggressive, protective, and territorial, causing tensions in the tank

These 3 simple facts point out an inevitable conclusion: you need to invest in a breeder tank. But what does that imply, and how do breeder tanks work? Fortunately for you, that’s exactly what we’ll be discussing today, so let’s dive right in!

What is a 40-Gallon Breeder Tank?

You would think that 40-gallon breeder tanks are just regular 40-gallon tanks turned into breeding setups. And you would be wrong.

The typical 40-gallon tank is generally tall and long, while the breeder one is wider with a larger base. The goal is to allow you to easily assess and catch your fry, which is often necessary when handling your growing fish community.

This means that you need to consider the tank’s size, shape, and base structure before getting the stand. 40-gallon tanks have wider bases, so you need to balance them carefully to prevent them from tipping.

Especially since you will be working with them regularly to relocate the fry, alter the aquascape, perform frequent water changes and maintenance, etc.

40-Gallon Breeder Tank Dimensions

The typical dimensions for a 40-gallon breeder tank revolve around 36x18x16 (Length/Width/Height.)

These may vary slightly, depending on the manufacturer, but make sure they’re as close to these values as possible.

Also, make sure you understand the differences between breeder tanks and regular 40-gallon pieces before buying your tank of choice.

For instance, high 40-gallon tanks can go as tall as 20 inches, while long designs can reach 48 inches in length. These can work as breeder tanks too, but they’re far from ideal.

How to Use a 40-Gallon Breeder Tank?

How you use your 40-gallon breeder tank depends on the fish species and the number of fry you’re getting. Each fish species requires specific environmental conditions in terms of water conditions and overall setup.

Here are some of the essentials to consider:

Breeding Tank for Cichlids

Cichlids require ample swimming space, a variety of hiding areas, and pristine water conditions.

These 3 factors alone should inform you quite well on the approach to consider.

A 40-gallon piece is optimal for cichlids as the available space allows you to craft the ideal layout for your cichlid young until they mature enough.

Consider the following tips:

  • Sand substrate – Cichlids require a fine substrate as they are notorious diggers. They will play in the substrate, look for food, and even bury themselves when resting or rattled. The sand substrate will also mimic the cichlid’s natural habitat allowing it to feel more comfortable in its improvised setup. Sand is naturally easier to clean, which is a blessing given that cichlids can be quite messy in general.
  • Hiding spots – Most cichlids prefer rocky layouts with a variety of hiding areas available. Provide your cichlids with plenty of caves and crevices for them to use as hiding, especially since fry and juvenile cichlids are shier at first. They will eventually become more familiar and at ease with their setup, but it may take time. Just make sure you don’t overdecorate their habitat. Cichlids are energetic fish that love to swim, play, and explore their habitat, so they need sufficient open swimming spaces for that.
  • Clean waters – Juvenile cichlids eat more often than adults and produce more waste as a result. Cichlids are also messy eaters, producing plenty of food leftovers in the process. These fish are extremely sensitive to ammonia and nitrites, so you need to have a good maintenance system in place to keep your cichlids healthy.

These fish will get hardier as they mature, but they require more personalized care during their first weeks of life.

Grow-Out Tank for Fish Fry

We should first define what a grow-out tank is. In essence, it is a tank with a specific purpose; either to house fish fry or quarantine newly purchased fish before adding them to the tank.

There’s no clear-cut use, but the concept is quite easy to grasp. In essence, you have a stable, personalized ecosystem to use as a temporary refuge for your fish, depending on their needs.

Can grow-out tanks be smaller than 40 gallons, I hear you ask? Yes, they can, but that’s not ideal.

One problem is that the tank will most likely house multiple fish and even multiple fish species. If you’re using your grow-out tank as a breeder setup, you want as much space as you can get; the 40-gallon setup should do for most fish species.

That’s because a small tank will hinder the growth of many fish species that require room to reach their full potential.

Then you have the layout management part, where you need sufficient room to add various plants, aquatic decorations, substrate, equipment, etc.

Even though the environment is temporary, your fish still need to be housed in an optimized setting for improved comfort.

Planted Fish Tank

40-gallon breeder tanks make for great housing options for planted fish setups. Many fish require heavily planted environments to remain safe and happy, and most of them are schooling or shoaling species.

The problem is that these fish also demand a lot of space, despite their small sizes. The reason isn’t the fish themselves but the plants’ presence.

You already know that plants produce oxygen which keeps the aquatic habitat healthier for your fish. But did you know that live plants can also kill aquatic life?

This generally happens in overplanted aquariums due to how the photosynthesis process works. In short, plants produce CO2 during nighttime.

The more plants you have, the more CO2 is produced at night, which can result in many fish suffocating to death. The math is simple.

A 40-gallon setup, at a minimum, is great at providing more room for increased aquascaping potential.

Now, you can have both sufficient live plants and adequate open space for environmental variation and lower risks of CO2 accumulation.

The extra room also allows you to clean the tank easier and prevents ammonia buildup due to excess dead plant matter.

Community Fish Tank

Everybody prefers community setups to single-species ones, and for good reasons.

Community tanks are more colorful and unique, allowing you the freedom to pair multiple different fish species, depending on compatibility and your own imagination.

The problem is that different fish species have different environmental requirements, so you need space to accommodate them properly.

Since the fish belong to different species, they are also prone to showcase aggression, territorial behavior, and bullying tendencies between each other.

The situation isn’t as bad with calmer and friendlier species, but it’s a risk you can never overlook. Again, the surplus of space allows you to manage the situation better.

With a 40-gallon tank at your disposal, you’re now free to add more live plants, rocks, and driftwood and increase the space your fish can use to move around and evade aggressors.

You also don’t want your fish to feel overcrowded since this alone can trigger their aggressive tendencies, raising the risk of tensions and confrontations.

Hospital or Quarantine Tank

Not many people give hospital or quarantine tanks their fair due, but they’re actually extremely important in the grand scheme of things.

Let me explain:

  • Quarantine tank – It is absolutely necessary when bringing new fish to your main tank. You don’t want to throw them into the general population without quarantining them for at least 2 weeks first. This will put your mind at ease that the fish doesn’t have parasites, bacteria, or any other type of infection or disease. The quarantine tank should be set up to your new fish’s requirements in terms of both water conditions and overall layout. The quarantine tank is also useful in cases of fish incompatibility and aggression. You simply use the tank to house either the aggressor or the aggressed for a while until you figure out the right course of action.
  • Hospital tank – This type of tank is an absolute necessity when dealing with sick fish. The major problem is that most fish disorders are highly contagious and can aggravate quickly. Most are also deadly, especially when affecting fish with compromised immune systems. The hospital tank serves as a clean, separate environment where you can place your fish during the treatment procedure. That’s because, in many cases, the treatment involves medication, and you don’t want to use these in the main tank.

A 40-gallon setup is ideal in both of these cases, given that you never know how the extra space can help you in the future.

Stand for a 40-Gallon Breeder Tank

A 40-gallon tank needs a sturdy and heavy stand that won’t tip off, move, or risk breaking under the tank’s weight.

Depending on the materials it’s made of, a 40-gallon tank can weigh around 60 pounds empty and more than 480 pounds filled up.

And when I say filled up, I only mean water and nothing else.

It’s not uncommon for a 40-gallon piece to jump the 500-gallon mark once you add the substrate, plants, rocks, fish, and whatever decorations you might use.

The stand to use should match the tank’s dimensions at a minimum. I recommend getting the stand with a slightly larger mounting base, though, as this gives you some wiggle room if you want to shift your tank to different positions.

When it comes to overall aesthetics and utility, these depend on your preferences.

Some stands come with open shelves, others have doors for a more intimate feel, and others have no depositing space at all.

The material is also crucial in this sense, and I say you should cut no corners when it comes to sturdiness and overall strength.

Whether you go for metal or wood-made stands, always make sure it’s strong enough to hold considerably more than 500 gallons. It’s always better to have a good margin of error to prevent accidents.

Finally, we should address the DIY aspect. Many people choose to build their breeder tank stands themselves, and while this sounds great in terms of the freedom you get, I advise against it.

This is primarily due to the tank’s weight. Even the smallest miscalculation in terms of material strength or actual building technique could spell disaster when you least expect it.

Stay away from any DIY job if you’re not proficient in the matter and haven’t built other stands before.

Buying a 40-Gallon Breeder Tank

If you’ve decided to get your 40-gallon tank today, I advise researching the topic thoroughly before getting it.

You can check Amazon, Petco, Petsmart, and even local fish stores to get a grasp on the multiple options available.

Most breeder tanks this size fall into the $100-600 range, depending on the manufacturer, shape, material quality, durability, etc.

You can adapt to your needs, preferences, and financial possibilities to get the exact piece you need.

But this is only possible by having a large pool of options at your disposal and checking multiple pieces to get a clearer picture of what you need.

Fish You Can Keep in a 40-Gallon Breeder Tank

Fortunately, a 40-gallon tank is more than enough to house a variety of fish species.

These include cichlids, guppies, platies, swordtails, plecos, etc. The main thing to consider is the fish’s size and their basic space needs.

Some fish require more space, while others do not, depending on their size and behavior.

Guppies, for instance, need approximately 2 gallons of water per fish. So, you can house a lot of them in your 40-gallon aquarium, around 20 or more, to be more precise.

Other species, like ram cichlids, need more space; you can only house 2 ram cichlids in your 40-gallon piece.

Always consider your fish’s needs before choosing their ideal tank size. You don’t want your fish to feel overcrowded.

This will not only reduce their comfort but can increase their aggression and stress levels significantly as well.

Also, keep in mind that keeping the fish in unnaturally small environments will hinder their growth.


A breeder tank is absolutely necessary thanks to its flexibility of use.

You can transform it into a quarantine environment, a hospital tank, a community habitat, and a fully planted setup for fry or smaller fish.

Choose your breeder tank carefully based on your fish’s needs, the tank’s sturdiness and dimensions, and the available depositing space.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.

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