Simulating rainy seasons in the aquarium
The subject content of this article may raise a few eyebrows, why would you want to replicate rainy seasons and even more so, how on earth can you do this in an enclosed aquarium. This article is designed to give you some tips on how to re-create this natural event that many fish experience in the wild and as you read through you will start to understand why this phenomenon is important to certain species of fish.
Breeding and rains
Well to answer the first part often fish breeders may want to use this practice to trigger spawning with certain species of fish, particularly wild specimens that may inhabit climatic conditions throughout a 12 month period. These fish will experience dry seasons where the water levels drop dramatically and rise again with the onset of the monsoons etc. this often triggers the fish to spawn as the higher water levels produced after long periods of rain provide better conditions for the fry that are produced. During the dry season many fish struggle to survive never mind breed so rain is welcomed and a new year of reproduction will begin. Often inexperienced breeders will try in vain to get some fish to spawn without even thinking of using this method, other ways to trigger the spawning is successful with fish from a steady climate but will not always work with other fish so do give this a try and you may be surprised at the results.
So how do we start off this process, very simply we just reduce the water level in the aquarium gradually, you may be tempted to do this in on go but I prefer to do it gradually as there are other factors that come into play as water levels drop and a bit of lateral thinking will make this all seem sensible. The deeper the water level the higher the water pressure at the bottom of the aquarium, of course in a tank that is say two foot deep the change is minimal but fish are very sensitive and can react to this, changing it gradually will mean the fish react less as well. Dissolved solids and minerals will increase in percentage, the same effect occurs as when water evaporates from the aquarium, yet again slowly does it. You are aiming to gradually get the water level to 25%-30% of its normal level. If there are heaters in the aquarium make sure that as the water level drops, they remain submerged or you will finish up making the heaters overheat and stop working, the same applies to the inlets on filters, keep the inlet pipes below the surface of the water.
Once the water level is decreased to the level required you can start to slowly fill the aquarium again to re-create the rainy season. I would normally leave the water level at a low for a couple of weeks just to give the fish the impression that they are in the dry season, filling the aquarium straight away will just mean that the fish think they are just going through a routine water change.
When re-adding the water to the aquarium, I always use cold water. This may go against all of the rules of fish keeping with tropical fish but you are trying to recreate rainfall and this will never be the same temperature as your tank water in nature. By cold water I do not mean straight from the cold water tap but water that is a few degrees works well and will not inflict any shock onto the fish. I raise the water level by a few inches each day and after a few top ups you may start to see your fish reacting to this practice, the males may become more interested in the females and start to swim around them displaying to attract their attention. These are good early signs that this method is working with your breeding fish and should encourage you to carry on with this method. Remember that you may have to re-position the heater and the outlets from the filters as the water level rises but try to keep the outlets splashing on the water surface to represent the rainfall.
Once the water level has reached the original level again your difficult fish should have provided you with signs of breeding or even some eggs for you to hatch out and raise the fry do not be put off if this method does not work the first time, patience will pay off eventually and you will finish up with breeding pairs of fish that keep you busy tending their young!