Because 1.026 is ideal for reefs but fishes can be kept in practically anything :P (I have kept mine for weeks without knowing that my salinity was at 1.031). You can keep softies in almost anything like 1.021, which is ideal for fish only systems (not the delicate ones like ricordia ofcourse) but for pretty corals, you should aim at something 1.024 to 1.026.
|