Ostracoda impairs growth and survival of Arapaima gigas larvae

Pirarucu larviculture in green water provides heavier fish and modulates locomotor activity

“…The type of larviculture water did not affect larvae survival rates, which were around 76-78%, but were lower than those observed in other studies on pirarucu larviculture (93 -99%) (Alcântara et al 2018;Araújo da Silva et al 2018;Gonçalves et al 2019). This could be due to the initial weaning period and the live food type supplied before the feed transition period, as pirarucu larvae fed Artemia nauplii and zooplankton until day 11 showed 99% survival after 21 larviculture days (Alcântara et al 2018) Survival in the initial pirarucu hatchery is related to many factors such as available food, size at the beginning of weaning, density in the tank, sanitary and feeding management (Gonçalves et al 2019). The use of microalgae in the larviculture rearing environment has been reported to shorten the feed-transition period without altering production rates, allowing to achieve higher survival rates, lower cost per larva and higher production yields than the traditional larviculture system (Jomori et al 2005).…”

“…Different upper case letters in columns for each behavior and light treatment indicate significant differences between water treatments (two-way ANOVA and Tukey test; p ≤ 0.05) after being fed Artemia nauplii for 15 days (Araújo da Silva et al 2018), and 93% after being fed Artemia nauplii and zooplankton for 11 days (Alcântara et al 2018). Pirarucu larvae fed only Ostracoda-rich zooplankton displayed an increased length of 62.7%, but lower survival (40%) than larvae fed zooplankton rich in cladocerans, copepods and rotifers (Gonçalves et al 2019). The zooplankton from natural environments (cladocera, copepoda, rotifera) is the main food item during the larval and juvenile periods of carnivorous fish like pirarucu (Lima et al 2018).…”

“…Optimal light conditions during fish larviculture increase growth and survival, and promote normal development (Villamizar et al 2011). However, under outdoor conditions, fish larvae are more susceptible to the action of predators (piscivorous birds, aquatic insects, bats) (Gonçalves et al 2019). Dominant larvae stand out in food competition, making access to food difficult for submissive larvae, which can become smaller and eventually die (Lima et al 2017).…”

“…In current pirarucu (Arapaima gigas Schinz, 1823) larviculture, larvae remain in outdoor ponds and are cared for by parents until they reach 7-10 cm in size, when they are collected and allocated to indoor tanks to be fed commercial diets (Pereira-Filho et al 2010;Halverson 2013). During the period under parental care, larval mortality rates can reach around 90% (Ono et al 2004;Pereira-Filho et al 2010;Gonçalves et al 2019).…”

“…An alternative to achieve higher zootechnical performance and survival rates of pirarucu larvae is the capture of larvae when they have an inflated vesicle and swim close to the breeder's head, transfer the larvae to the laboratory and train them to receive formulated feed by weaning, which can increase larval survival up to 95% (Araújo da Silva et al 2018;Gonçalves et al 2019). Weaning consists of gradual feed transition, also known as co-feeding, and is characterized by progressively reducing live food concomitantly with increasing inert feed supply until the fish have adapted to exclusive inert food ingestion (Azevedo et al 2016).…”