Ichthyofauna in the Hellenic freshwaters is quite diverse consisted of 161 species (including 28 non-natives), out of the 546 native species in PanEuropean level. However, the status of many aquatic ecosystems is currently degraded as a result of a variety of anthropogenic impacts. This has direct reflection on the conservation status of the indigenous and native fish species whose populations are in many cases declining in favor of the invasive ones. Prussian carp (Carassius gibelio) is probably the most dominant invasive species and currently is considered as naturalized in about 26 lake and river basins. Its successful adaptation and proliferation is mainly attributed to its dual reproductive mode (allogynogenetic and gonochoristic), the opportunistic-omnivorous feeding habits and the ability to withstand and flourish in adverse ecological conditions. Accordingly, it exerts competitive, as well as destructive effects upon the indigenous fish species (sperm parasitism, antagonism for food, spawning grounds and spawning substrates) and therefore, efforts are needed to sustain a relative balance of the populations. This review aims to critically discuss the status of C. gibelio in Greece, the intrinsic causes of establishment and the observed impacts on ecosystems. Finally, reasonable actions are proposed related to exploitation of C. gibelio stocks and a path model for the protection of native fish species and their ecosystems.

This paper presents records extending or confirming the distribution of Mediterranean species. Three alien algae are included, namely Codium taylorii reported for the first time from the Aegean and Turkey (Izmir Gulf), Caulerpa racemosa var. cylindracea (Karpathos and Chalki Isl., Aegean Sea) and Ganonema farinosum (Karpathos Isl., Aegean Sea). As far as animals are concerned, Litarachna divergens (Acari: Hydrachnidia) was recorded (Side, Eastern Mediterranean) and represents a new amendment at genus level for Turkish fauna. Other invertebrates include alien species such as the crabs Dyspanopeus sayi (Lago Fusaro, SW Italy), Percnon gibbesi (Larnaca, Cyprus; Karpathos and Chalki Isl., Aegean Sea) and Callinectes sapidus (Voda estuary, NW Greece), the nudibranch Aplysia dactylomela (Boka Kotorska Bay, Montenegro), the gastropod Conomurex persicus (Karpathos and Chalki Isl., Aegean Sea) and the bryozoan Electra tenella (Livorno harbour and Messina Straits area). The alien fish Siganus luridus, Siganus rivulatus, Fistularia commersonii, Sphyraena chrysotaenia and Sargocentron rubrum are also reported from the islands of Karpathos and Chalki, and Pteragogus pelycus from Heraklion Bay, Crete. In addition, new localities for four rare Mediterranean inhabitants are given: the cephalopod Thysanoteuthis rhombus (NW Sardinia) and the fish: Lampris guttatus (Calabria, S Italy), Petromyzon marinus (Gokova Bay) and Remora australis (Saronikos Gulf), while the opisthobranch gastropod Cerberilla bernadettae is reported for the first time from the E Mediterranean (Cyprus). Finally, three species of the Aegean ascidiofauna are recorded for the first time: Lissoclinum perforatum, Ciona roulei and Ecteinascidia turbinata. Furthermore, it was established that Phallusia nigra has extended its distributional range to the north of the Aegean Sea.

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Sex control in aquaculture aims to benefit from desirable traits expressed differentially by each sex. In ornamental fish, such manipulation can be profitable, especially in species with high price discrepancy between sexes. This is particularly true for the fancy males of Siamese fighting fish (Betta splendens Regan, 1910), which are very popular aquarium pets. Therefore, fry originating from controlled reproduction were fed initially with artemia nauplii from day 4 post-hatch up to day 7 post-hatch. Subsequently, they were orally administered with 17a-methyltestosterone (MT) (via inert feed) in four concentrations (1, 2, 3, and 4 mg/kg of hormone in feed) for eight weeks. The experiment was repeated with fry of the same origin in identical conditions with the exception of a prolonged supply period (from day 4 post-hatch until day 11 post-hatch) of artemia nauplii enriched with red pepper. The results demonstrated that the 3 and 4 mg/kg doses resulted in 100% masculinization and the extended provision period of enriched artemia nauplii increased the survival rate of the offspring. However, mortality rate increased in all hormone treated groups in both experiments, partly due to the prolonged hormone administration period. Therefore, oral administration of low MT doses is effective for the masculinization of Siamese fighting fish.

Dolphin therapy emerged during the 1950s. The work of Dr. John Lilly played an important role, since he investigated the impact of dolphins on disabled people. From 1978 onwards, the therapeutic aid of dolphins was further advanced, especially after the success of Dr Davis Nathanson with Down-syndrome children and Dr. Ludmila Lukina, who developed many therapeutic methods. The therapeutic method is based on the hypersonic stimulus transmitted by the dolphin sonar (a strong organ at the top of the head, which helps dolphins to produce and receive sounds) towards the central nervous system of humans, resulting in the synchronization of brain hemispheres for a certain period (brain waves are concerted in both hemispheres regarding frequency and phase), which is in turn contemplated as neurologically uncommon. The scientific experience of supplementary therapeutic approaches using dolphins reinforces the classical medical therapies and has provided solid proofs of positive effects of such programmes on: autism, Rett syndrome, Down syndrome, mental delay, brain paralysis, depression, cognitive difficulties, hyperkinetic syndrome. Therapeutic centres, such as Dolphin Assisted Therapy, provide various therapeutic programs of different duration, targeting to assist people with a variety of problems. Scientific results documented that dolphins affect the speech during interaction with humans, decrease the depression symptoms and reduce the pain in people suffering from multiple sclerosis. The present work provides up to date data regarding dolphin therapy in a worldwide context. It is actually a thorough literature review, which attempts to cover a gap in the field of therapeutic contribution of animals to human's health.