Opened the bottle (after quite a few time) this morning to find out that the colour was a bit funny... very cloudy (like schweppes citrus) instead of the usual transparent. It also had quite a few little specs.
I suspect the turbidity is caused by sulphur precipitating out. If it was me I would discard the solution.
Ilford data sheet for Rapid Fixer: "Unreplenished ILFORD RAPID FIXER working strength solutions should last for up to 6 months in full tightly capped bottles"
"Full, unopened bottles of ILFORD RAPID FIXER concentrate stored in cool conditions, 5–20ºC (41–68ºF), will keep for two years. Once opened use completely within six months and keep all bottles tightly sealed until used."
I have seen it before, initially the fixer will still work (clear film) but who knows what the capacity now is and since it is an inexpensive material and directly affects the life expectancy of the negatives I replaced it immediately.