Blue (Philippine Blue) Angelfish
Pterophyllum scalare
About this strain
Philippine Blue — often just called Blue — carries a gene that dramatically increases iridophore (reflective cell) coverage, giving the body a stunning steel-blue to turquoise sheen, especially visible along the flanks and into the fins. Combined with other genes it creates some of the most spectacular compound strains in the hobby (Blue Blushing, Blue Zebra, etc.). The blue coloration is most vivid in good light at the right angle — it has an almost metallic, shifting quality. The PB gene is autosomal dominant with dosage effect; fish homozygous for it (PB/PB) tend to be even more intensely colored.
Origin
Developed by breeder Loh Han Yick in the Philippines during the 1990s–2000s. The strain was introduced to Western hobbyists in the early 2000s and quickly became a cornerstone of modern angelfish genetics.