lower un-ionized ammonia levels between 12 and 24 hours in the
treatments with addition of salt could be explained by the death of the
fingerlings. Since during this period of the experiment the mortality
was total, there was almost no additional production of ammonia.
Since lethal concentration of un-ionized ammonia for a 24-hour period
was 0.24 mg/L for channel catfish, Ictalurus punctatus (Tomasso
1994), probably un-ionized ammonia levels (up to 0.143 mg/L) de