Most of the Freshwater Aquarium Fishes, especially the fishes from Amazon spawns after the long dry season with the advent of the Rains. I have tried to do some research on the same and have come up with a day wise chart. It is interesting and may help you to spawn a large number of fishes from Amazon.
Why do the fishes spawn in the Rainy Season?
Most often they spawn when the rainy season begins, because it brings increased food supply and increased possibilities for the fry to find food and shelter.
The following is a compilation of a way to breed fishes that come from areas with marked dry and rainy seasons, e.g. the Amazon and Rio Negro areas of South America. Data and ideas have been collected from a lot of different sources; including books, friends and the Internet, and are based on my own experiences breeding cichlids and characins from South America.
If you see the real event that goes in with the starting of the Rains in the Amazon basin are:
- Low pressure
After a long period of high pressure at the end of the dry season, the barometric pressure falls in connection with the first rain. - Increased food supply
After a starvation period during the end of the dry season the food supply increases drastically. Certain species look like skeletons at the end of the dry season, and have perhaps been without food for more than a month. Certain species even eat detritus to get some nutrition. - Changed food types
During the dry season the scarce food might consist of bottom dwelling animals (red mosquito larvae) and decaying plant parts. When the rainy season starts the food changes to insects that fall onto the surface: mosquito larvae (especially white and perhaps black) and other water insects, pollen from flowers, seeds, fruits, fresh leaves and eggs, and fry from other species that have begun to spawn earlier. - Increased water flow
The rain results in increased flow of water. The fish become more active. Some species migrate upstream to get to calmer and more suitable spawning areas. - Increased oxygen levels
Rain that falls on the water surface increases the oxygen level in the water. Increased water flow also makes the oxygen level increase. In many cases a high oxygen level is a condition for the eggs and fry to make it during their first days. - Dilution of dissolved substances in the water
The longer the dry season lasts, the more salts, humic substances and organic material are concentrated in the water that remains. When the rain starts the concentration of these substances decreases due to dilution. The river, the stream etc. is diluted with rainwater that has zero hardness, which lowers the hardness and often even the pH. - Change in water temperature
Water temperature is often lowered due to cloudiness and the cold rainwater. In high terrain temperature differences are often greater than down in the lowlands (10ºC compared to a few degrees). - Change in water depth
Increased water volume causes the water to deepen. Water pressure at the bottom increases and the fish get a larger vertical swimming space. Distance to the water surface will be longer for species that go to the surface to catch air. - Spawning sites become available
At the end of the rainy season there is often water only in the middle of the river or stream, and there are very few plants or hiding places. With increasing water depth, the fish can find newly flooded areas with plants, roots, tree trunks and shadows, in which to hide eggs and give the fry a better chance to hide. - Changes in the light
The amount of light and duration of light decreases due to cloudiness in connection with the rain. Certain parts of the day can be very dark during the most intense rain. With more clouds in the sky it takes longer in the morning before it gets light and it darkens faster in the evening.
Even light angles vary from one part of the year to the other. The further from the equator, the more the variation.
Note that certain species want almost complete darkness to spawn (they live under dense vegetation, among tree roots and in black water). - Increased plant plankton level
When the rainy season occurs this increases in certain waters. This is also a signal to the adult fish to spawn because there is food for smaller fry. - Right time of the year
Certain species have a very strong "biological clock" that is linked to when the rain and dry seasons occur in their natural distribution area. - Other fish spawn
Hormones in the water from other fish spawns might prompt another species to spawn. - Sound
Even the rain's splashing against the surface might be a signal to spawn. Maybe also the sound of thunder.
This simulated dry and rainy season cycle takes about 4 weeks to go through.
How do we simulate these things in the tank?
Below are suggestions on how to simulate the different stimuli that are listed above into a DAY-WISE scheme.
Please Note that Low pressure is of course impossible to simulate in a tank, so keep an eye on the weather forecasts and start a simulated rainy season during the passage of a period of low pressure.
If you known the substrate to provide, vegetation to add for a particular species of fish then below is the DAY-WISE scheme to stimulate dry and rainy season:
End of rainy season:
Still some food, and the water level has not started to lower.
Still some food, and the water level has not started to lower.
Day 1. Feed about 1/10 of normal. The lights should now have a level between full power and "cloudy", about 14 hours. Filter running at full speed.
Day 2. Lower the water level about 10%, feed 1/10 of normal. Add some calcium carbonate and magnesium sulphate to raise total and carbonate hardness 1 degree each. (An alternative is to take out 20% of the water and add half the amount with hard tap water if that's available.) Add a dose of plant fertilizer according to instructions for your product (gives more dissolved salts in the water).
Day 3. Lower the water level about 10%, skip feeding. Increase the temperature about one degree.
Day 4. Lower the water level about 10%. Increase total and carbonate hardness 1 degree each. Feed 1/10 of normal. Put peat, alder comes, leaves, etc. in the water. Tannins etc. will be leached from these items over the coming days.
Beginning of the dry season:
Food supply decreases and ceases. Water level and current decreases. Temperature of the remaining water increases.
Food supply decreases and ceases. Water level and current decreases. Temperature of the remaining water increases.
Day 5. Lower the water level about 10%, skip feeding. Increase the temperature about one degree. Decrease the flow by adjusting the filter. Check pH.
Day 6. Lower the water level about 10%, feed 1/10 of normal.
Day 7. Lower the water level about 10%. Increase total and carbonate hardness 1 degree each. Stop feeding until day 21. Increase the temperature about one degree.
Day 8. Lower the water level about 10%.
Day 9. Lower the water level about 10%. Increase total and carbonate hardness by 1 degree each. Shut off air stones. Take out the filter and clean it. Let the filter run in another tank so it has a working bacterial culture when it's needed in a week.
Day 10. Lower the water level about 10%. The water level should be down to 25% of the tank's capacity. The temperature should be around 28 degrees. Put peat, alder comes, leaves, etc. in the water. Add plant fertilizer. Increase the lighting to max. Take away any floating plants. Start an infusoria culture. Check pH.
Day 11-19. Leave the fish in peace.
Beginning of rainy season:
The first clouds can be seen in the sky but no rain has started to fall.
The first clouds can be seen in the sky but no rain has started to fall.
Day 20. Clean the filter that has been working in another tank. Decrease the lighting, both the intensity and the length (down to about 10 hours). Take out the peat, leaves etc. Check the pH.
First rainfall:
Day 21. Put the floating plants back in. Add more plants of the type the fish like for spawning. Add clean, as soft as possible, water (preferable RO), about 20% of the tank volume. The water's temperature should be about 3 degrees lower than that of the tank. Put in the filter and run it at half speed if possible. One could try to turn off the light for a couple of hours in the middle of the day to simulate thick clouds. Lower the heater temperature by 2 degrees. Feed a little with mosquito larvae and newly hatched brine shrimp. Add infusoria so that the water gets a slight cloudiness.
Day 22. Add the equivalent of 20% of the tank volume, with water about 5 degrees lower in temperature than the tank. Run the filter at full speed and make it "splash" in the surface. Lower the heater temperature by 2 degrees. Feed a lot and often. Add infusoria so that the water gets a slight cloudiness. Add a vitamin product and plant fertilizer according to instructions for your product.
Day 23. Add the equivalent of 20% of the tank volume. The water temperature should be about 5 degrees lower than that of the tank. Add aeration at a low level. Lower the heater temperature by 2 degrees. Feed a lot. Add infusoria so that the water gets a slight cloudiness.
Day 24. Turn off the heater if the fish can take such low temperatures. Aeration at half speed. Fill the tank. The water temperature should be about 5 degrees lower than that of the tank. If you can, open a window during the night to lower the temp. further. Feed a lot. Add infusoria so that the water gets a slight cloudiness.
Height of the rainy season:
Day 25. Aeration at full speed. Change 50% of the water volume. Feed a lot.
Day 26-?. Carry on as Day 25 until they spawn!.
Please share with me if your fish spawns ....
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