<b>Alternative liming blends for fish culture</b>

Abstract

ABSTRACT. Calcium carbonate (limestone) is a safe but slow-acting product for aquaculture liming. Calcium oxide (lime) is a fast-acting but dangerous product. It would be interesting to have simultaneously a safe and fast-acting liming product. The present work aimed to evaluate two alternative liming blends for tilapia culture. The culture water was initially acidified with HCl. Next, the same quantity of CaCO 3 (control), Na 2 CO 3 +CaSO 4 or Na 2 CO 3 +CaCl 2 was applied to the culture water. There were also nonlimed tanks. One hundred and twenty Nile tilapia juveniles (1.6 ± 0.1 g) were stocked in twenty 250-L culture tanks for 10 weeks. All products used were similarly efficient in increasing the alkalinity of water. The probable better environment for algal growth in the limed tanks caused an increase in the DO 2 concentrations and a decrease in CO 2 , total ammonia nitrogen, nitrite and phosphorus, in relation to the non-limed tanks. The highest final body weight of fish was observed in the Na 2 CO 3 +CaCl 2 tanks. The lowest final body weight was verified in the CaCO 3 tanks. It was concluded that the alternative blend of Na 2 CO 3 plus CaCl 2 is a better liming product than the standard CaCO 3 for Nile tilapia culture.Keywords: limestone, lime, tilapia, alkalinity, aquaculture.Misturas alternativas para calagem em piscicultura RESUMO. Carbonato de cálcio é um produto seguro, mas de ação lenta para calagem em aquicultura. O óxido de cálcio é um produto de ação rápida, mas perigoso. Seria de interesse ter um produto para calagem em aquicultura que fosse simultaneamente seguro e de ação rápida. O presente projeto de pesquisa teve por objetivo avaliar duas misturas alternativas para calagem no cultivo de tilápia. A água de cultivo foi inicialmente acidificada com HCl. Em seguida, a mesma quantidade de CaCO 3 (controle), Na 2 CO 3 +CaSO 4 ou Na 2 CO 3 +CaCl 2 foi aplicada à água. Havia ainda tanques não submetidos à calagem. Cento e vinte juvenis de tilápia do Nilo (1,6 ± 0,1 g) foram estocados em 20 tanques de cultivo de 250 L por dez semanas. Todos os produtos testados foram igualmente eficientes no aumento da alcalinidade da água. Os tanques submetidos à calagem apresentaram maiores concentrações de O 2 D e menores de CO 2 livre, nitrogênio amoniacal total, nitrito e fósforo. O maior e o menor peso corporal final dos peixes foram observados nos tanques Na 2 CO 3 +CaCl 2 e CaCO 3 , respectivamente. Concluiu-se que a mistura alternativa Na 2 CO 3 +CaCl 2 é superior ao CaCO 3 na calagem de tanques de tilápia do Nilo.

<b>Tolerance of Nile tilapia juveniles to highly acidic rearing water

“…According to El-Sherif and El-Feky (2009), the optimal range of water pH for rearing Nile tilapia, Oreochromis niloticus, is between 7 and 8. However, recent data obtained in our laboratory by Nobre et al (2014) suggest that the optimal range of water pH for farming Nile tilapia juveniles in green waters is wider than that reported by El-Sherif & El-Feky (2009), ranging from 5 to 8. The Nile tilapia, therefore, adapts and grows well in moderately acidic waters (Nobre et al, 2014).…”

“…However, recent data obtained in our laboratory by Nobre et al (2014) suggest that the optimal range of water pH for farming Nile tilapia juveniles in green waters is wider than that reported by El-Sherif & El-Feky (2009), ranging from 5 to 8. The Nile tilapia, therefore, adapts and grows well in moderately acidic waters (Nobre et al, 2014). In that work, however, the growth performance of tilapia was not evaluated under stronger water acidity (pH< 5).…”

<b>Reassessment of the suitable range of water pH for culture of Nile tilapia <i>Oreochromis niloticus</i> L. in eutrophic water

“…These authors, however, have reared tilapia fingerlings in oligotrophic clear waters, in tanks with 100% daily water exchange. Consequently, there were low concentrations of toxic metabolites in the water, such as ammonia and H 2 S. However, Nile tilapia juveniles have grown surprisingly well on acidic organic-matter rich waters (pH < 6) in previous studies carried out in our laboratory (Nobre, Lima, & Magalhães, 2014;Rebouças, Lima, & Cavalcante, 2015;Silva, Santos Lima, Vale, & Carmo, 2013). Colt, Momoda, Chitwood, Fornshell, and Schreck (2011) have also found that O. niloticus could be transferred from pH 6 -7 to as low as pH 4.2 without problems.…”

Utilization of Lime Derived From Mussel Freshwater Shells (Pilsbryoconcha exilis) to Increase Swamp Water pH For Catfish (Pangasius sp.) culture

“…Relationship between cultural time (day) and soil's and water's pH showed that at the same dosage (6 ton/ha), mussel shell lime that was activated become CaO was increasing pH faster than calcite as common material of lime. The calcium carbonat (calcite) is a safe but slow-acting product, meanwhile the calcium oxyde fast-acting product for aquaculture liming [8]. Based on neutralizing value (NV, the relative abilities of liming materials to neutralze acidity), pure calcium carbonate is 100%.…”