 Rachovia hummelincki, |
History
The type locality of Rachovia hummelincki is situated in the South- West of the peninsula Paraguana, North Venezuela. The first discovery was made by P.W. Hummelinck, a Dutch explorer of the Dutch Lower Antilles and Venezuela, in 1937.
I went to the peninsula several times to collect this species. Found it in January 2010 for the first time together with Siegmund Sladkowski from Germany but all fishes were in the process of dying as result of insufficient oxigen and overheated water in their biotope and the pairs I took with me didn't recover at my home.
Recently at the end of October 2011, I sailed over from Aruba to Paraguana and collected this species at 2 different locations. The first was Cerro Atravesado where I found them dying before, the second was Adaure. Both populations look very similar if subadult...let see what it becomes when they grow to adulthood.
I myself went also in 2006 and 2008 and 2009 to Colombia on a mission to find this species on different locations around Santa Marta and more to the south as far as Bosconia were they can be found in open landscape in annually evaporating pools.
Rachovia hummelincki forms with the other components R.brevis , R. maculipinnis, R. pyropunctata and R. splendens the genus Rachovia. This species often is found in muddy pools, often together with Austrofundulus guajira and other Austrofundulus members who may predate on this smaller species as wel.
The colour variability whitin Rachovia hummincki is rather high. To the right at the top you see the nominal form, lower a male with white marking in the caudal. Lowest to the right a male showing a black spot at the flanks. It depends on their mood if males show a black marking just behind the gill- cover or not.
In the reproduction series below you se an variant wit orange at the upper- and lower edge of the caudal, even with some orange in the anal fintip.
Reproduction
As Rachovia hummelincki is wide spread in Venezuela and Colombia and these coumtries have huge dimensions it is likely the habitats differ in soiltype, temperatures and rain cycle. The local species did all adapt to their specific situation and even than this situation fluctuate from year to year. So it is very difficult to give specific time tables for incubation or for temperature and water quality and measurements.
To give a sort of indication of the time the species need to incubate I will supply you with the most average information. Please keep in mind that this vary's from one location to the other. Normally 12 to 16 weeks the eggs need to be ready for watering. They are ready if the iris is clearly visible inside the egg schell. It further depends on temperature and humidity of the storage conditions.
The higher the temperature - up to 35 C. is possible - the earlier the development. This can speed up the development at the best to 6 weeks but it is not recommended as there is a major loss of eggs possible. The humidity is also a factor and the wetter the peat the earlier the development. But also here is this not without danger of funges attacs if peat is stored to wet.
The species mostly live on clay bottoms that affect the waters pH they live in and mostly the pH is around the neutral level. So, low pH can also effect the survival of the eggs but does not has effect on the time of development.
It is wise to choose a spawning medium that has not a very low pH. Therefore I recomment the use of Coco - peat that is boiled well before it is used.
Rachovia is a productive Genus and many eggs can be produced by one single pair if food of good quality is given. They do not like dry foods but do like life food as mosquito larvae and other small insects. In most cases they also love fresh meat but this is not always good for their guts and overfeeding with meat can lead to siknesses or dead.
Juveniles eat artemia from the moment they are born. The growht is very rapid and whitin 5 weeks they are able to spawn themselves. Females are, at a certain point, to be seperated from the males for reasons they grow less rapad in the first weeks and can become prey to the bigger males easely.
During my collecting tour recently in January 2009 I was able to collect the species at its terra typica on the peninsula Paraguana, Venezuela. Unfortunately all fishes were dying as result of low and very hot water situation. None of the fishes survived the first 2 weeks and no eggs were spawned either.
Remarks :
Within one population some males show a second orange- red band also in the upper part of the tail which is not the standard for this species. This was also the case with the strain that was taken from COL 2006-02. (see image)
Variations
Map
Meristics
Max. size 8.0 cm.
Dorsal 11.3,
Anal 13.4,
D/A 6.0,
LL scale count (average)31.1
Pre- dorsal length to % SL – 66 %
Literature
Beaufort, L.F. de. 1940. Freshwater Fishes from the Leeward Group, Venezuela and Eastern Colombia. Stud. Fauna Curacao, Posa de San Antonio, east of Carirubana, Paraguana peninsula, Venezuela.