Abstract: The present paper embodies,in continuance to Part Ⅰ,the result of my study of the protozoan parasites from another species of Chinese pond fishes Mylopharyngodon piceus.Sixteen species(not including the species of Myxosporidia)have been recorded from 184 individual fishes.The 11 known species are Cryptobia branchialis Nie,Bodo caudatus Dujardin,Glugea hertwigi Weissenberg,Dermocystidium percae Reichenbach-Klinke,Ichthyophthirius multifiis Fauquet,Chilodonella cyprini Moroff,Hemiophrys macrostomaChen,Trichodina pediculus Mueller,T. bulbosa Davis,Glossatella cylindriformis Chen,Trichophyra senensis Chen.The diagnosis of five new species are summarized as follows: 1.Trypanosoma mylopharyngodoni Chen sp.nov.(Figs.1—4)is of sinuous,elongated and spindle form.It has a breadth of 1.4 microns and total length of 44.2 microns.The free flagellum is 12.5 microns long.The kineto- nucleus is small and ovoid or spindle in shape,and situated 5.3% of the body length from the posterior end.The blepharoplast is very difficult to discern. There is a well-developed undulating membrane which has 5-6 folds. An oval nucleus is situated 40% of the total body length from the anterior ex- tremity and occupying the entire width of the body.The cytoplasm contains a few vacuoles. 2.Eimeria mylopharyngodoni Chen sp.nov.(Figs.9—23)has a spherical oocyst,mearsuring 13.1 microns(12.3—13.9μ)in diameter,has a thick, smooth and transparent wall.The cytoplasm has a coarsely granulated appearance. In mature oocyst,the spore is oval in shape and contains two banana- shaped sporozoites and a spherical spore residual body.The oocystic residual body is also present.There are 1-2 small,dark,irregularly shaped polar inclusions.Sporulation is completed within the host.The endogenous cycle of development occurs usually in mucus of the anterior portion of the small intestine,but sometimes it may occur in the tissue of the liver and kidney. 3.E. intestinalis Chen sp.nov.(Figs.24—33)is a small species and its body appears smaller than the preceding one.Oocyst is spherical in shape, mearsuring 9.2 microns(8.5—9.7μ)in diameter,and has a thick,smooth and faintly greenish wall.The cytoplasm has a finely granulated appearance. In mature oocyst,the spore is oval in shape and contains two banana- shaped sporozoites.The spore residual body is larger than that of E. mylopharyngodoni.The oocystic residual body is absent.There are 1-2 small, dark,irregularly shaped polar inclusion.Sporulation is also completed within the host.The endogenous cycle of development occurs in the mucus of the anterior portion of the small intestine. 4.Glugea intestinalis Chen sp.nov.(Figs.39—43)was found from the mucous tissue of the small intestine of this host.The spores are ovate and measure 6.2 microns long by 3.6 microns broad.In cross-section,they are circular in outline.An oval or ellipsoidal polar capsule occupying about the half or two-third of length of the spore,is seen at the anterior half.Within this capsule,in some specimens,coils of the polar filament could be observed. The rest of the spore is filled with cytoplasm which contains a rounded nucleus and a large oval vacuole at the posterior end. 5.Trichodina nasi Chen sp.nov.(Figs.63—68)is found from the nasal cavity of the host.It has an apple-shaped body in side view.The denticulated ring is well-developed and consists of 19-22 denticles,the usual number being 20-21.The hook has a sickle-shaped outline,the concave side of which is thicker and stains much more deeply than the convex side.The rays are long,slender and sharply pointed at the end.The striated band has 8 to 9 bars between each two denticles,the usual number being 9.The diameter of the denticulate ring is 13.1—16.9 microns(average 14.5μ),and that of the striated band being 23.1—32.3 microns(average 24.2μ).The parasite varies from 7.7—12.3 microns(average 9.8μ)in height.Although the macronucleus has the usual horseshoe-shaped outline,the middle region of which is often larger than the portions of two arms.A spherical micronucleus is located near the end of one arm.