“…However, the majority of studies on the application of saponins in aquaculture have focused on their use as natural growth promoters when included in feeds for fish and shrimp (Francis, Makkar, & Becker, 2002; Kelly & Kohler, 2003; Paray, Hoseini, Hoseinifar, & Van Doan, 2020; Serrano, Focken, Francis, Makkar, & Becker, 2000; Yang, Tan, Dong, Chi, & Liu, 2015). Only a few authors have assessed their potential benefits when applied directly in the tanks or ponds, in order to reduce the concentration of ammonia within the culture environment (Castillo‐Vargasmachuca et al, 2015; Fayed et al, 2019; Khalil, Saad, Ragab, & Mohammed, 2015; Santacruz‐Reyes & Chien, 2010, 2012). Oak ( Quercus robur ) is known to have a high content of bioactive compounds (Burlacu, Nisca, & Tanase, 2020).…”