Dear Jack,

as you probably know, I have given a lot of information on the weather and information on rainy and dry season of the upper Orinico system elsewhere. What you are asking now is on one side tough, on the other easy, because of the following:

1. The area is very close, just a little north, of the equator therefore the daylight and nightlight is exactly devided in a 12/12 hour retual all year - except for the moon phase at night, which you can see on almost any calender. So you have no season-light-changes at all. Only exception might be for o quarter of an hour (rarely more and seldom for days) that in the rainy season it get's dark during this (short) period.
2. I am not convinced that this – the daylight's (small) difference – has anything to do with the breeding season of the fishes. The the moon light yes, certainly.
My experiance is that they breed (most of them, in nature), when they know the food for the young to grow up is available, which is only (and best) with the begin of the rainy season. The parent fishes know that for sure, also when there is a change in the weather condition (better than any human weather-technology). If it is later, they spawn later.
You see this is (I am sure) in the gen of fishes. I found i.e. in new Guinea, were there is really no rainy and dray season (as it rains all year long), that there fishes have adaped to be continuous breeders, most of the species lay mate and lay eggs all year around, but not in Amazonia, or Central Afica, or Indochina.

Now my advioce is: if you want to study the breeding behaviour in the upper Orinoco system (which is very similar to most of the Amazon basin), you have to put your (fish)clock to the normal season (which, as I said above can change from time to time. Unfortunately with the tremendous global warming everywhere today a precise prediction is difficult.
Just last week I had planed to collect again a new angel fish species I found last year, it is the dryiest time there in the Demini usually January-February. It is a left affluent of the Rio Negro. But a local fishermen told me it is higher, the water level, than ever in history... so any normal weather condition is history...
It will make it difficult now for you too simulate, although the fish will know...
Anyhopw, the suggestion I have is: February-April (latest) is you clock for that reason for fishes to spawn. Very rarely already in January (but i.e. no one knows now, if the waters will receed ones more befor they finally rise...).

We have a lot of obstacles to consider, obstacles we might find very difficult, but our beloved fishes not. I am sure (and have done it many times successfully except with P. altum and the Hyphessobrycon erythrostigma from Peru) to breed my fishes in an habitat (decorated environment) as close as possible to the authentic natural biotope of the species. And than, at the time of the year.

Actually that is how one was finally able to spawn Heckel discus (something extreme rare), because he follwed my advice perfectly and in Febrauary (as in nature) they spawned...

So I hope this will give you more to think and do, sorry if there is no 100% correct recepie, but I guess that does not exists anyhow.

All the best from the walking (and often in the sleep, as helped me many times to find my fish) dictionary.

Always

Heiko Bleher

他豐富的經驗果真給我完全不同的感受

 

Hi,
sorry you have no name, but anyhow I will try to give you some answers. But when reading the below, please keep in mind the following:
1. To my experiance during the last 40 years (and it can also be seen in my new book: Bleherh's Discus were I have 250 Amazon chemical water parameters recorded during the last 4 decades (mostly recorded by myself at the dates mentioned) water tempertures have risen (like air temperatures = the famous global warming effect). And the below values are from some years back.
2. One can never be completely precise in tropical areas with mesurements taken only in one spot (equatorial regions specially), as there is a lot of fluctuation in the water temperatures - dpending on the water layers (which naturally fishes have total access to, it is not a aquarium). For instance just now, during the last 4 weeks I did two Amazon expeditions. One in the upper Rio Negro system and right at the equator line the water temperature varied within one small habitat tremendously. On the top level it was 29.3°C at 14:30 (black water) and in 1 m of depth was a layer of water which had only 26.9° C and further down again around 28° (and in the very shallow edge - in bright sunlight up to 31,8°C).
I have found in many parts of aquatic habitats, specially in tropical regions around the world, such a temperature variation in waterlayers.
3. At night, if that is in the rainy or dry season, the water temperature cools from the bottom up and therefore the top layers are torwards the morning hours the warmest (that is why you find species near the top layer at night, those which during daytime go further down again).
4. Most Amazon/Orinoco regions go through a period of 1-2 weeks each year (hardly more - only in rare areas upo to 3 or 4 weeks maximun) of what the Brazilians call "friagem" - the so called "ajú" or "repiquette" (see also my book for more details). This means in that period, which varies in each region, the temperature suddenly drops by several degrees clecius (up to 10°C), in the air and in the water. And as mentioned almost regular each year (than many fishes die in nature - often millions - see also in my book).

As mentioned: these are some of the important facts in nature to consider always.

Now to your questions:
My values for rainy season is that daytime (vor the upper Orinoco - white waters) average between 28 to 30°C in the upper levels (not in bright sunlight, for those habitats ad 1 to 1.5 °C); for clear water habitats during day, the water temerature may vary in the upper level slightly less (and black waters have normally higher temeratures, of 0.5 to 1.0°C).
At nighttime in the rainy season depending on the layer drops by some degrees celcius (as well as in the dry season). Data for the region runs from 25.5 to 27.5°C (in the morning hours is the lowest temperature on the top levels, around 4-5 AM) in white waters; in clear waters even a little less and in black waters you have it again a little higher (0.5 to 1.0°C). But all have the lowest temperture in the early morning.

For the dry season the temperatures in aquatic habitats vary never much to the rainy season (except for what I mentioned above under 1.-4.). As you may know, in most tropical regions it rains only for a few minutes each day during the rainy season and than the bright sunlight comes out again. (Naturally there are some days always when it rains longer, or some times for a few days - but that is rare in teh Amazon/Orinoco, but not though in New Guinea, India, etc...)
You can have an average of 28.5 to 30.9 (or even 31)°C in white waters at day (always shady areas); a little less in clerar waters and 0.5 to 1°C higher in black waters.
During nighttime the temperature in white waters my go down to 26.0°C; in clear water a little less and in black waters hardly below 27°C.

I hope this answers your questions.

All the best, and next time give your name, as it would be polite.

Heiko Bleher
(that is my name)