F8 to SW?

[MatthewLaw]

Greetings All- Can F8s have a long and healthy life in SW (1.023) just like they could in bracksih (1.007)? I know we have discussed putting F8s in with FW but what about F8 in SW? Thanks. -Matt

[yunachin]

Figure Eights are best at low end brackish. 1.005 or so. I believe that RTR kept his for several long years this way. Full saltwater is something they just cannot tolerate.

[CoreyK]

I'm sure being euryhaline fish they would live in saltwater, but it isn't their natural environment and I doubt they'd be healthy.

[Nick]

I tried it for a couple months when I had no other options, it's certainly far from a death sentence. They do indeed survive, but immune function does not seem to be all it could be, and once I had a brackish environment cycled for them, they were brought down to low brackish again.

[MatthewLaw]

thanks for the help and experience story!

[riggers]

The trouble with fish is the process called osmosis whereby water moves through a semipermeable membrane (the fish's skin) to dilute the substance on the other side (in this case FW tries to dilute SW). So with a freshwater fish, if you were to put it in saltwater, the fish will attempt to dilute the saltwater on the outside of it to make it the same concentration as the freshwater inside it's cells. Obviously a fish cannot dilute the whole ocean,or even a tank of saltwater, so the fish gets 'dehydrated' and eventually dies. Similarly with saltwater fish, if you put one in freshwater it takes on too much freshwater to try and dilute the saltwater inside it. There are obviously some exceptions to this such as GSPs and Salmon who will actually go from FW to SW, but only about 2% of fish can do this. F8s are brackish and can therefore put up with a small change, if done slowly, and it's probably best if they're not in the saltwater for long periods of time.

[Nick]

Yes, mine got an hour and change of acclimation time, both ways, I'm sure that was a very important part of it being lower in stress on them.

[riggers]

Yeah acclimation helps a lot. Also, I think some fish are just naturally stronger than others and so can withstand harsher changes etc.