1. Sodium , calcium , strontium , 

 magaesium , potaasium , lithlm, 

 barium , manganous and cobeiltouB 

 ions have a relatively low tox- 

 icity for fish. With but fsw 

 exceptions, they have not been 

 observed to cause toxicity at 

 concentrations less than ^0 p. p.m. 



The California State Water Pollution 

 Control Board (12) lists some additional 

 factors concerning water quality and their 

 effect on fish life. These factors are 

 summarized below: 



a. Algae have affected fish life by 

 production of toxic metabolic 

 products; by clogging fish gills 

 when tbey die in huge numbers; 

 and by depleting the oxygen sup- 

 ply when they die and decompose 

 in large numbers. 



b. Arsenic (a ccnpcneat of insecti- 

 cides, weed killers, and many 

 industrial WEustes) - from the 

 meager infozmation available, it 

 appears that arsenic compound 

 concentrations of less than 1.0 

 p. p.m. £ire not harmful. 



c Bacteria - soine favor fish life 

 by creating decomposition pro- 

 ducts necessary in the food rhwin; 

 others may be haimful by deple- 

 ting the oxygen or by causing an 

 infection in the fish (such as 

 columnaris disease). 



d. Benzene hexachi oride (an insecti- 

 cide) - gamma Isomer reported to 

 be toxic to fish at 0.05 p.p.m. , 

 the delta at 0.2 p.p.m., and the 

 beta at 2.0 p.p.m. 



e. Bromine - fish siirvived for 48 

 hours in concentrations of 10 

 p.p.m. of molecular bromine. 



f . Cadmium - minimum lethal concen- 

 tre xon for stickleback has been 

 reported as 0.^ p.p.m. Cadmium 

 salts may be more toxic. 



g. Chlordane (an insecticide) - dust 

 toxic to f ingerllngs of bass and 

 bluegllls at concentrations of 

 0.2 p.p.m. 



h. Chlorides - 400 p.p.m. in fresh 

 water reported hamful to trout. 



i Color - no reported direct effect on 

 fresh-water fishes. 



J. Cresols - 10 p.p.m. fatal to any 

 fish under prolonged exposure. 



k. Cyanides - toxic to sensitive fish 

 at concentrations of less than 0.1 

 p.p.m. 



1. D.D.T . (an insecticide) - concentra- 

 tions of less them 0.1 p.p.m. may be 

 lethal to fish life. 



m. Dissolved solids - no appreciable 

 effect observed if solids below 400 

 p.p.m. 



n. Fluorides - Goldfish survived 100 

 p.p.m. for over h days. 



o. Fomaldehyde - 10 p.p.m. had no 



apparent effect on rainbow trout in 

 3 days. 



p. Hardness - An increase in water 

 hardness tends to reduce the tox- 

 icity of many compoxmds. 



q. Nitrates - no observed effect on 

 fish life; favor growth of fish by 

 promoting growth of food chain. 



r. Oil - 0.4 ml. oil per liter of water 

 reported to be toxic to fresh-water 

 fish. Kerosene applied at the rate 

 of 25 gallons per acre, as a larvi- 

 cide, had no effect on fresh-water 

 fish. 



s. Pentachlorophenol (wood preservative 

 and also used for slime and algae 

 control) - lethal to fish life at 

 concentrations of 0.2 to 0.6 p.p.m. 



t. Phenol concentrations of 1.0 p.p.m. 

 or less will probably be safe for 

 most fish. 



u. Riosphates - not toxic to fish life 

 and may be beneficial by increasing 

 food chain. 



V. Selenium - constant exposure to 

 traces of selenium has produced 

 toxic effects. 



13 



