That's 6 parts per thousand, folks. As in 6,000 parts per million. Seawater is 36 parts per thousand. That's one reason why HSB do so well in my ponds. They can tolerate salinities up to nearly full seawater. My well water is about ten times saltier than you'd want to drink. Interestingly, my water is similar in salinity to a bluegill's body. That may be one reason why my bluegill grow so well and have so few disease problems. They are expending little or no energy to maintain an osmotic gradient. All the more energy to go towards growth. I've also found that redear sunfish thrive in levels like this. I've got some that grew quite large this summer, although I'm hesitant to tell anybody how big. I don't know if anybody would believe me. :p
