I was first introduced to the concept of permanent breeding aquariums about ten years ago when reading an article by renowned Swedish aquarist Helmut Pinter. He in turn had been inspired to write the article by aquarists in Eastern Europe. After having tried keeping permanent breeding aquariums over a number years I have only good things to say about them and would like to recommend everyone to try this method of fish breeding.

What is a permanent breeding aquarium?

A permanent breeding aquarium is as the name suggests an aquarium used to breed fish in which eggs, fry and parents are allowed to coexist. This term is usually used when talking about breeding egg scattering species without any fry protection since it is normal to leave egg and fry guarding species with their young, while breeders usually remove the parents of egg scattering species once they eggs are laid to avoid that the eggs and fry are eaten by the parents.

A permanent breeding aquarium is decorated to make the survival rate of the eggs and fry as high as possible with the parents still in the aquarium.  It is true that the survival rate of the fry is lower in a permanent breeding tank than it would be if the parents are removed, but this is compensated by the fact that the parents can breed more often. This method is especially suitable for species that usually lays a few eggs each day and therefore yields small fry batches when bred in a conventional fashion.

A permanent breeding aquarium is a one tank solution that will eliminate the need for separate fry, breeding and holding tanks, freeing up aquariums that the aquarist can use to keep other species or setup more permanent breeding aquariums increasing the total number of fry bred. Another benefit of the permanent breeding aquarium is that the surviving fry usually is of higher quality than the fry raised in aquariums where the parents have been removed. Weak and low quality fry are the first to go in a permanent breeding aquarium and the natural selection will therefore weed out low quality fry.

Lets recap:
Drawbacks of permanent breeding aquariums:

1. Lower survival rate among the fry

Benefits of permanent breeding aquariums:

1. Higher quality fry
2. More frequent spawnings. (This is especially important with species that breeds often but produce a low number of eggs in each spawning.)
3. Eliminates the need for separate breeding, fry and holding aquariums.

Personally I think the advantages out-weigh the drawbacks, but you might not agree depending on your needs and the amount of aquariums you have access to etc.

How many fry survive?
The answer to this question does of course depend on the fish species you keep and how you decorate your breeding aquarium. Personally I have found that you can expect about 40-50 juvenile fish of "sell size" each months from an established 25 gallon/100 L permanent breeding aquarium. It usually takes about 6 months for a tank to become established and start producing "sell sized" fry.  Some species gives you a lot more fry but it is relatively few that give you less than mentioned above as long as you keep the water quality up and the water parameters right.

Setting up a permanent breeding aquarium

Setting up a permanent breeding aquarium is done in much the same way as you would set up any other aquarium, you still need to let it cycle etc, the only difference is that a well thought through decoration is much more important in a permanent breeding aquarium. You want to create a decoration that contains ideal spawning areas for the parents while at the same time maximizes the amount of hiding spaces for the fry and thereby maximizes the survival rate of the offspring. The key to achieving this is to get the right plants and plenty of them. You will also have to take special care to make sure that the filtration doesn't suck the fry in.

It is hard to give any general instructions as on how to decorate the spawning areas since different species prefer different environments to spawn in. You will have to research the species you plan to keep in the permanent breeding aquarium and setup spawning areas accordingly. 

Despite the differences in breathing behaviour exhibited by the many different species of fish, the fry protection can generally be arranged in a similar way in all aquariums. This is done by making sure that there are suitable plants present at all levels on the tank. By this I mean that there should be plants at the surface, on the bottom, and in the middle while still of course leave open areas for the parents. I recommend using a plant such as water sprite on the surface since their roots create a lot of hiding places for the fry.

On the bottom I recommend dense plantations of java moss covering more or less the entire bottom of the tank. A problem with java moss is that it can grow too fast and come to dominate the aquarium. It can therefore be a good idea to choose another "aquarium moss" if available in your local fish store. The reason for me recommending java moss and not any other species is that java moss is the only species that is more or less universally available in aquarium stores.

I have now covered the bottom and surface of the breeding aquarium, but we still need to create safe areas in the middle of the tank. How are the fry otherwise going to get from the surface from the bottom safely?  My way of doing is that is to plant the sides of the aquarium very densely with a fine leafed plant. I prefer to use C. demersum but there are a number of other suitable plants such as Cabomba species and many Rotala species. I personally have had great success using a wide variety of plants.

Once all plants are in place and they have been given time to grow dense you will have a fully functioning permanent breeding aquarium. It is now time to adapt it for the fish you want to breed. Exactly what this means depends on the species you are going to breed, but in broad terms it means making sure that the pH-value, water hardness and temperature is optimal for breeding the fish you want to breed. In a normal holding tank you don't need to hold your fish in the water they need to breed all the time, but in a permanent breeding aquarium you do, at least if you want to get as much as possible out of it.

Feeding in a permanent breeding aquarium

You will have to feed both the fry and the adult fish in a permanent breeding aquarium. Feeding fry of different sizes and the parents might sound like a pain, but another benefit of permanent breeding aquariums is that there usually is enough food among the plants for the fry to eat during their first days until they can accept newly hatched brine shrimp. The fry will then usually do well on a diet of brine shrimp until they are large enough to accept the same food as the parents eat. If you breed small species it might actually be enough just to feed the fish brine shrimp but that requires a lot of brine shrimp.  I usually feed the adult fish one thing and the fry another, while trying to vary the diet as much as possible for both the adults and the fry (even if the fry do well on nothing but brine shrimp). I will not elaborate on this further as there are plenty of other information available on AC Tropical Fish (aquaticcommunity.com) and elsewhere on the topic of fish and fry food.

Suitable species

Most egg scattering species are suitable for permanent breeding aquariums if the size of the aquarium is chosen with the size of the species in question in mind. There are however some species that are especially suitable for this type of tank. Such species include species that are not especially prone to eating their own fry, such as rainbow fish and white cloud mountain minnows. Species that lay a few eggs each day are also very suitable for this type of breeding and breeding such species in a permanent breeding aquarium can often be more productive than any other method of breeding. My recommendation to anyone is to not be afraid to experiment. Most species can very successfully be breed in this type of setup. I have personally breed a broad variety of species using this setup including but not limited to neon tetras, congo tetras, black skirt teras, serpea tetras, several rainbow fish species, rasbora species, danio species, and numerous barb species such as cherry barb, copper barb, tiger barb, tinfoil barb, odessa barb, etc etc etc.