Analytical investigations on Gafrarium Tumidium clam tissue using nondestructive thick target Ion Beam Analysis (IBA) techniques at the 3 MV TandetronTM are presented. PIXE (Particle Induced X-ray Emission), PIGE (Particle Induced Gamma-ray Emission), and RBS (Rutherford Backscattering) techniques were concomitantly applied using a 3 MeV proton beam normal to the target in vacuum. A comparison is made with analytical results previously obtained on this sample by Instrumental Neutron Activation Analysis (INAA) with neutron irradiation at the TRIGA reactor in Pitesti, Romania, as well as thin target PIXE with 3 MeV proton beam at the 9 MV FN Van de Graaff Tandem accelerator of IFIN-HH. The sample was supplied by IAEA-MEL Laboratory, Monaco, in the frame of an inter-laboratory exercise organized for the determination of trace elements in marine biota IAEA-461, to monitor analytical capabilities of the participating laboratories and to allow them assessing the quality of provided results. Our contribution to this exercise was based on long-lived INAA, the reported elements being Ag, As, Au, Ba, Br, Ca, Cd, Ce, Co, Cr, Cs, Eu, Fe, Hf, Hg, K, La, Lu, Mo, Na, Ni, Rb, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, U, Yb, Zn (33 elements). Thin target PIXE was used to determine P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Br, Rb, Sr, and Pb (19 elements). From them, P, S, Cl, Ti, V, Mn, Cu, and Pb are complementary to INAA. Thin targets were prepared from chemically mineralized solutions of the sample and comparator standards, with Y added as internal standard. With reference to thick target IBA, PIGE technique was able to determine F, Mg and Al, besides Na (also obtained by INAA), Cl and P (also obtained by PIXE). Major light elements C, N, O, as well as Cl, Na, and Ca could be determined by RBS. The knowledge of sample matrix is necessary for PIGE analysis to calculate stopping power values for protons in sample and comparator standards. Thick target pellets were prepared using hydraulic press. The results obtained by INAA and IBA on Gafrarium Tumidium clam (IAEA-461 Reference Material) are in agreement with the certified mass fractions assigned for As, Ca, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, V, and Zn, as well as information values given for Al, Mg, and Sr. The elements Cu, Mn, Pb, and V could be determined by PIXE, Al and Mg by PIGE, while As, Ca, Cd, Co, Cr, Fe, Hg, Ni, Se, Sr, and Zn by long-lived INAA.