The aim of the present study was to evaluate the effects of diet with different microbial concentrations on the growth and length-weight relationship of Trichopodus trichopterus. For this aim a study was designed with four experimental treatments and the control to evaluate different microbial concentrations on growth and length-weight relationship. The counts of bacteria that were used for dietary supplementation were 1×104, 2×104, 3×104 and 4×104 CFU g-1 in T1, T2, T3 and T4 treatments, respectively. The results indicated that the use of 3×104 CFU g-1 concentration increased the length, and a positive allometric growth was observed. The higher length frequency was estimated in T3. The results indicated that the use of microbial additives with proper concentration causes different allometric growth.Cilj ovog istraživanja bio je ispitati učinke hranidbe nadomjestkom različitih koncentracija mikroorganizama na rast i dužinsko masene odnose Trichopodus trichopterus. U svrhu tog cilja, studija je dizajnirana s četiri eksperimentalna tretmana i kontrolom za procjenu različitih koncentracija mikroorganizama na rast i odnos duljine i mase. Broj bakterija koje su se koristile za hranidbeni dodatak su 1×104, 2×104, 3×104 i 4×104 CFU g-1 u T1, T2, T3 i T4 tretmanu. Rezultati su ukazali da se upotrebom 3×104 CFU g-1 koncentracije povećava duljina, a uočen je pozitivan alometrijski rast kod istraživane vrste. Veća frekvencija duljina procijenjena je u T3. Dobiveni rezultati ukazuju da primjena različitih koncentracija probiotičkih organizama u odgovarajućem slučaju uzrokuje različit alometrijski rast riba
