Suggest you get a water test prior to adding stuff. Salt would likely not hurt any. Here is some info on salt and HSB but keep in mind some fish don't have the high salt tolerance as HSB.
https://srac.tamu.edu/index.cfm/getFactSheet/whichfactsheet/54/ Hybrids survive and do well in a
wide range of environmental conditions.
A temperature range of 4 to
33 C is acceptable, but optimum
growth occurs within a temperature
range of 25 to 27° C. Hybrids are
generally stocked into freshwater systems
but they do well in salinities of
O to 25 ppt, and some can survive
salinities up to full strength seawater
(35 ppt). Dissolved oxygen levels as
low as 1 mg/l can be tolerated for a
short period of time, but optimum
dissolved oxygen levels range from 6
to 12 mg/1.
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