First record of non-native Xiphophorus maculatus (Günther, 1866) (Cyprinodontiformes, Poeciliidae) in the state of Maranhão, northeastern Brazil

During a field expedition in 2020, we recorded specimens of an invasive platy fish, Xiphophorus maculatus, in the state of Maranhão, Brazil. This new occurrence, in the Municipality of São Luis, is only the second time that this non-native species has been found in northeastern Brazil. We provide an updated list of all invasive species recorded from the island of São Luís, highlighting the negative impacts they may confer for the native biodiversity.

Determination of thermal tolerance parameters of swordtail (Xiphophorus helleri) and platy fish (X. maculatus) acclimated to different temperature levels

Thermal tolerance parameters of swordtail (Xiphophorus maculatus) and platy (X. helleri) at three acclimation temperatures were determined in the study. The CTMin values at 20, 24 and 28°C acclimation temperature were 9.41,10.42 and 11.95°C respectively for platy and 9.38,11.5 and 13.23°C for swordtail, while CTMax values were 37.41, 39.19 and 40.52°C for platy and 36.94, 38.89 and 40.07°C for swordtail. Accordingly, acclimation temperature affected the lower and upper temperature tolerances of fish by 3-4 °C. The CTMin ARR values varied between 0.42-0.42 in swordtail and 0.20-0.34 in platy, while CTMax ARR ranged between 0.29-0.48 in swordtail and 0.33-0.44 in platy depending on acclimation temperature. Thermal tolerance polygon area of platy (232°C2) was slightly higher than that of swordtail (217.3°C). The fact that both fish species have lower temperature tolerances limits their geographic distribution and aquaculture in subtropical climates where the water temperature drops to 10°C in winter.

PENGARUH PENAMBAHAN VITAMIN C PADA PAKAN BUATAN TERHADAP LAJU PERTUMBUHAN DAN KELANGSUNGAN HIDUP BENIH IKAN PLATY SANKE (Xiphophorus maculatus)

Tujuan penelitian ialah untuk mengetahui dosis maksilam vitamin C (kontrol, 50 mg/kg pakan, 100 mg/kg pakan dan 150 mg/kg pakan.) yang dapat diberikan kepada ikan. Manfaatnya ialah sebagai penambah kelangsungan hidup dan laju pertumbuhan ikan platy terbaik. Rancangan penelitian yang digunakan ialah Rancangan Acak Lengkap dengan empat perlakuan dan tiga ulangan. Benih ikan platy memiliki panjang tubuh ikan 0,3 cm ± 1,26 berasal dari Fajar Aquatic Bogor, ditebar secara acak ke dalam 12 akuarium dengan kepadatan 60 ekor dan ikan dipelihara selama 28 hari. Parameter uji adalah laju pertumbuhan bobot spesifik, laju pertumbuhan panjang spesifik, efisiensi pakan dan tingkat kelangsungan hidup. Hasil penelitian menunjukkan bahwa penambahan vitamin C berpengaruh secara nyata (P<0,5) pada kinerja pertumbuhan dan efisiensi pakan ikan platy. Kinerja pertumbuhan (laju pertumbuhan bobot spesifik : 1,78±0.22 %/hari, laju pertumbuhan panjang spesifik : 0,67±0.10 %/hari) dan efisiensi pakan: 63,31± 10,46 terbaik terjadi pada perlakuan dosis vitamin C 150 mg/kg pakan. Penambahan vitamin C pada pakan tidak berpengaruh secara nyata (P>0,5) terhadap kelangsungan hidup ikan platy.Kata Kunci :penambahan vitamin C; ikan platy; kinerja pertumbuhan

Coral platy fish Xiphophorus maculatus hormonal induction to improve mass spawning efficiency

Coral platy fish has a unique reproduction due to ovoviviparous (live-bearer) reproduction. The large scale production of coral platy fish has several constraints due to the inconsistent seed birth period, which causes variations in the fry size. This makes it difficult for ornamental fish cultivators for production process efficiency and market criteria fulfillment that demands size uniformity. This study aimed to synchronize the broodstock birth period of coral platy fish by testing the hormone oxytocin and prostaglandin-2 α (PGF2α) through immersion methods with different durations. This study used a factorial randomized design with 21 treatments and 3 replications for each hormone type. The PGF2α hormone doses used were 0; 0.01; 0.1 and 1 mL/L, while the oxytocin hormone doses used were 0; 0.1; 0.2; 0.4 mL/L with immersion duration of 4, 8, and 12 hours, respectively. The results showed that the treatment dose of 1 mL/LPGF2α with 12 hour duration had a significant effect (p <0.05) compared to other treatments, the immersion group with 12 hour duration obtained a significant difference to the length of other treatments both at the percentage of broodstock giving birth and number of seeds. The hormone treatment had no significant effect on broodstock and seed survival (p> 0.05). Keywords:mass induction, oxytocin, prostaglandin-e2 α (PGF2α), mass birth, livebearer ABSTRAK Ikan plati koral memiliki reproduksi yang unik karena bereproduksi secara ovovivipar (livebearer). Produksi ikan plati koral dalam skala besar dihadapkan kendala akibat waktu kelahiran anak yang tidak serentak yang menyebabkan keberagaman ukuran anak ikan plati koral. Hal ini menyulitkan para pembudidaya ikan hias untuk efisiensi proses produksi dan memenuhi kriteria pasar yang menuntut keseragaman ukuran. Penelitian ini bertujuan untuk menyeragamkan waktu kelahiran anak induk ikan plati koral dengan uji coba pemberian hormon oksitosin dan prostaglandin-2 α (PGF2α) melalui metode perendaman dengan durasi waktu yang berbeda. Penelitian ini menggunakan rancangan acak faktorial dengan 21 perlakuan dengan 3 kali ulangan untuk masing-masing jenis hormon. Dosis hormon PGF2α yang diuji adalah 0; 0,01; 0,1 dan 1 mL/L, sedangkan dosis hormon oksitosin yang digunakan adalah 0; 0.1; 0.2; 0.4 mL/L dengan masing-masing lama perendaman 4, 8, dan 12 jam. Hasil yang diperoleh menunjukkan bahwa perlakuan dosis 1 mL/L PGF2α dengan lama waktu perendaman 12 jam memberikan pengaruh yang nyata (p <0.05) dibandingkan dengan perlakuan lainnya, kelompok perendaman dengan durasi 12 jam memberikan perbedaan yang nyata terhadap lama perlakuan lain baik pada parameter persetasi induk melahirkan dan jumlah anak yang dilahirkan. Perlakuan hormon tidak memberikan pengaruh yang nyata terhadap kelangsungan hidup induk dan anak yang dilahirkan (p >0.05). Kata kunci: induksi massal, Oksitosin, prostaglandin-2 α (PGF2α), kelahiran masal, livebearer

First record of non-native platyfish, Xiphophorus maculatus (Günther, 1866) (Cyprinodontiformes, Poeciliidae), in the Jaguaribe River basin, northeastern Brazil

We provide the first record of Xiphophorus maculatus (G&uuml;nther, 1866) in a river basin in the northeastern Brazil. Specimens were collected in the Jaguaribe River basin, Jo&atilde;o Pessoa, Para&iacute;ba state, Brazil. Two hundred eighty-one specimens, corresponding to 143 males and 138 females of X. maculatus, were collected at nine sites along the basin, from 2017 to 2019. Specimens total length ranged from 17.5 to 26.6 mm in males and from 11.7 to 32.7 mm in females. Introduction of non-native species greatly threatens the biological diversity worldwide. When introduced into a new habitat, X. maculatus usually decreases microcrustacean, macroinvertebrate and native fish populations.