gogolanu wrote:mar interesa daca sie cineva care este diferenta sexuala la plecostomus cenusiu marime 40 cm incerc de ceva timp reproducerea la aceasta specie si nu stiu diferenta sexuala dupa parerea mea femela mai mica si cu alte desene zici cai alta specie :ycard:

Planetcatfish.com wrote:

Sexing most species is quite simple when you know what you are looking for. The majority of species can be sexed by the presence of odontodes on the fins, posterior, interopercular, or sides of the head. This will vary with the species being worked with, but can be easily researched by looking at good photos of mature individuals. More often than not, the fish you're working with will show strong enough signs of their sex that research won't be required.

If this technique doesn't apply to the species you're working with, the fish will either have to be vent checked or scrutinized for proportional differences in the shape of the body and head. Both of these methods require that the fish are mature and you should have several specimens to compare. Vent checking is the easiest of the two. The fish are simply viewed from below, with a magnifying glass if necessary. The vent of a mature female has a rounded shape to it and may be distended if she is ripe with eggs. Most females will show an extreme bulge around the vent if they are nearly ready to spawn. Males can be a little more difficult depending upon the species. The vent will be smaller and has a flap of muscle that lays over it and gives it a rod shape. I'm not completely sure on the evolutional reason for the muscle there, but believe it is to direct the sperm back into the cave toward the eggs as they are being laid.

In order to compare shapes of the fish for sexing, the fish have to be mature. This just can't be done reliably before then. Males appear to get a great deal of detail in the shape of their head when compared side-by-side with females. This is to include several depressions and peaks in the profile of the head. In species where this applies, the female normally has a very rounded head without much detail to the shape.

lukaboy wrote:

Planetcatfish.com wrote:

Sexing most species is quite simple when you know what you are looking for. The majority of species can be sexed by the presence of odontodes on the fins, posterior, interopercular, or sides of the head. This will vary with the species being worked with, but can be easily researched by looking at good photos of mature individuals. More often than not, the fish you're working with will show strong enough signs of their sex that research won't be required.

If this technique doesn't apply to the species you're working with, the fish will either have to be vent checked or scrutinized for proportional differences in the shape of the body and head. Both of these methods require that the fish are mature and you should have several specimens to compare. Vent checking is the easiest of the two. The fish are simply viewed from below, with a magnifying glass if necessary. The vent of a mature female has a rounded shape to it and may be distended if she is ripe with eggs. Most females will show an extreme bulge around the vent if they are nearly ready to spawn. Males can be a little more difficult depending upon the species. The vent will be smaller and has a flap of muscle that lays over it and gives it a rod shape. I'm not completely sure on the evolutional reason for the muscle there, but believe it is to direct the sperm back into the cave toward the eggs as they are being laid.

In order to compare shapes of the fish for sexing, the fish have to be mature. This just can't be done reliably before then. Males appear to get a great deal of detail in the shape of their head when compared side-by-side with females. This is to include several depressions and peaks in the profile of the head. In species where this applies, the female normally has a very rounded head without much detail to the shape.

Deci spor la treaba!