A method for detecting Candidatus Branchiomonas cysticola in coldwater fish, comprising: providing a sample potentially containing one or more nucleotide sequences of a pathogen in a coldwater fish; providing an oligonucleotide primer pair defining the 5' ends of two complementary strands of a double stranded target sequence on the one or more nucleotide sequences of the pathogen, the oligonucleotide primer pair comprising a first primer and a second primer; providing an oligonucleotide probe having a sequence complementary to a segment of the double stranded target sequence, a fluorescer molecule attached to a first location on the oligonucleotide probe, and a quencher molecule attached to a second location on the oligonucleotide probe such that the quencher molecule substantially quenches the fluorescer molecule whenever the oligonucleotide probe is not hybridized to the segment of the double stranded target sequence and such that the fluorescer molecule is substantially unquenched whenever the oligonucleotide probe is hybridized to the segment of the double stranded target sequence; providing a polymerase; blending the sample, the oligonucleotide primer pair, the polymerase, deoxyadenosine triphosphates (dATPs), deoxycytidine triphosphates (dCTPs), deoxyguanosine triphosphates (dGTPs), and deoxythymidine triphosphates (dTTPs) in a container to form a polymerase chain reaction mixture; subjecting the PCR mixture to insulated isothermal polymerase chain reaction (iiPCR) by heating the bottom of the container at a fixed temperature to form a PCR product; and detecting the PCR product to identify the double stranded target sequence; wherein the first primer has the sequence of SEQ ID NO: 1, the second primer has the sequence of SEQ ID NO: 2 and the oligonucleotide probe has the sequence of SEQ ID NO: 3; or wherein the first primer has a sequence selected from then group consisting of SEQ ID NOs: 23, 25, and 27, the second primer has a sequence selected from the group consisting of SEQ ID NOs: 24, 26, and 28 and the oligonucleotide probe has the sequence of SEQ ID NO: 29. providing a sample potentially containing one or more nucleotide sequences of a pathogen in a coldwater fish; providing an oligonucleotide primer pair defining the 5' ends of two complementary strands of a double stranded target sequence on the one or more nucleotide sequences of the pathogen, the oligonucleotide primer pair comprising a first primer and a second primer; providing an oligonucleotide probe having a sequence complementary to a segment of the double stranded target sequence, a fluorescer molecule attached to a first location on the oligonucleotide probe, and a quencher molecule attached to a second location on the oligonucleotide probe such that the quencher molecule substantially quenches the fluorescer molecule whenever the oligonucleotide probe is not hybridized to the segment of the double stranded target sequence and such that the fluorescer molecule is substantially unquenched whenever the oligonucleotide probe is hybridized to the segment of the double stranded target sequence; providing a polymerase; blending the sample, the oligonucleotide primer pair, the polymerase, deoxyadenosine triphosphates (dATPs), deoxycytidine triphosphates (dCTPs), deoxyguanosine triphosphates (dGTPs), and deoxythymidine triphosphates (dTTPs) in a container to form a polymerase chain reaction mixture; subjecting the PCR mixture to insulated isothermal polymerase chain reaction (iiPCR) by heating the bottom of the container at a fixed temperature to form a PCR product; and detecting the PCR product to identify the double stranded target sequence; wherein the first primer has the sequence of SEQ ID NO: 1, the second primer has the sequence of SEQ ID NO: 2 and the oligonucleotide probe has the sequence of SEQ ID NO: 3; or wherein the first primer has a sequence selected from then group consisting of SEQ ID NOs: 23, 25, and 27, the second primer has a sequence selected from the group consisting of SEQ ID NOs: 24, 26, and 28 and the oligonucleotide probe has the sequence of SEQ ID NO: 29.