You should be ok. This assumes you did not stock lots more HBG than BG and CNBG. First you did not list GSF as a stocked species so there are no GSF in the pond. HBG cannot turn into GSF. They can reproduce and possibly back-cross with the BG and CNBG. You do not want the HBG X HBG offspring in the pond but they would only be very small numbers. The more the HBG cross with BG and CNBG the more the GSF genes in the offspring are diluted. Because BG reproduce in far greater numbers than HBG over time the GSF genes from the HBG are diluted to the point of being irrelevant.