There is very little deviation from our system in any of our spawning attempts. The only variation of any significance is the size of the spawning tank.
Our preferred tank size for spawning is a 10 gallon tank (approximately 40 liters). We use 5 gallon tanks during periods when we are working with large numbers of pairs, but under normal situations we use 10 gallon tanks.
All of our spawning tanks have glass covers with a way to slip an electrical cord and an air hose through or around the top and into the tank. Usually we pass the electrical and air lines pass through a clipped corner of the glass top. All of our spawning tanks also have a mechanism that allows us to quickly open the tank top to remove a fish or to feed the fish. We have a number of different way that the hoses and cords get into the tank...and an equally large number of ways that the tanks can be opened...but all the tanks have these elements.
The power cord would be for a heater.
We like to use a 25 water submersible heater in particular we use a heater made by Hagen called a Visaderm Heater. We have found that they put off enough heat to take a 10 gallon tank into the low 80 F range, are small enough not to take up too much room and are economical. Economy is a good thing as we have found ourselves dropping heaters on more than one occasion.
The air hose is for the sponge filter.
Although Bettas tend to prefer water with less current than most fish, filtration remains important. We know that the breeding pair will not be in the tank for a long period of time but the filter is there for a couple of very specific purposes. First, the water will be in better condition when the fry begin to hatch if a mature sponge filter is placed in the tank from the very first day. Additionally, a mature sponge filter will have a good infusoria associated with it and will allow the soon to be hatched fry an additional source of food. We use small round filters made by Lee and Hydro for our spawning tanks, both brands have been altered somewhat by shortening their lift tubes.
We clip the uplift tube of either brand of filter in half. The uplift tube can now be place In a tank with the proper amount of water.
Five gallons of water is used in a 10 gallon tank and about three gallons in a five. The 10 gallon tank allows for a bit more flexibility in controlling the water quality because of the extra water.
Java Moss is also added to the tank with two purposes in mind. When the female is introduced to the male we prefer to see her approach the nest immediately. We always feel that a quick approach is a good sign. We have noticed that if the female does not head for the nest first, she will be looking for a place to hide. If she does approach the nest first, she will not stay too long and will end up needing a place to hide. The Java Moss affords her that opportunity. However, we have found that a good hunk of Java Moss will be laden with infusoria and like the mature sponge filter, offers an additional source of food for the fry.
Temperature is very important. The ideal temperature for spawning Betta splendens is 82 degrees Fahrenheit. A degree plus or minus will have some effects. Two degrees plus or minus will have a profound effect. We test the temperature prior to the fish being added to the mix. So how do you tell the temperature without a thermometer? You don't...use one.
We do not "sterilize" the tank prior to setting up this environment. We do rinse the tank well, but use no chemicals (not even salt) to clean the tank.
A piece of plastic grocery sack that has been roughly cut into a four inch diameter circle is floated onto the surface of the water. We like to use white plastic. We prefer a somewhat round(ish) shape but are not sure if the fish really care about the shape of the plastic. We like to place the circle in a front corner of the tank. By pulling one edge up onto the glass, the capillary properties of the water will hold the plastic in place. It will stay in place throughout the entire process and into the third week of the fry care until we remove it and through it away. It is the only piece of the environment that we do throw away.
A glass chimney is placed in the tank. We place the chimney on the same end of the tank as the plastic circle. The chimney is taller than the water is deep so the female can't swim out. We have not had a situation where the male jumped in with the female or the female jumped in with the male (yet, I'm sure). The chimney is placed about 6 inches back from the front of the tank giving the male room to swim back and forth, build the nest and when the time comes to release the female, the chimney will be far enough away from the nest to allow the chimney's removal without disturbing the nest. The chimney is for the female of course but we place it in the tank prior to adding either the male or the female to the environment.
When the tank is set, we introduce the fish we have chosen for the spawning.
Good notes help.