parasitic diseases are harmful and limiting factors in breeding and rearing ornamental fish industry. in this study, 400 apparently healthy ornamental fishes from five species (each species 80 specimens) including: goldfish (carassius auratus), guppy (poecilia reticulate), angelfish (pterophyllum scalare), discus (symphsodon discus) and sailfin mollies (poecilia latipinna) was obtained from a l...

Little is known about the mechanisms individuals might use to compare group sizes when making decisions about group membership. One possibility is that animals use ratio to determine differences in group sizes. Weber’s Law states that the ease of any numerical comparison is based on the ratio between the stimuli compared; as the ratio becomes smaller the comparison becomes more difficult. We se...

Genetic parentage analyses provide insights into mating systems and have revealed widespread evidence for polyandry in natural populations. Here, we use 5 microsatellite markers to estimate female mating rates in a feral population of green swordtails, Xiphophorus helleri, a live-bearing poeciliid fish that has become a model system in the study of precopulatory mate choice and mating competiti...

Female green swordtails, Xiphophorus helleri, possess a preference for the multicomponent male sword. Previous work suggests that this female preference is a result of a pre-existing receiver bias favouring a sword and has contributed to sword evolution via intersexual selection. We use video presentations to investigate how females respond to components of this composite trait. Complete swords...