Effects of Fish Oil-Enriched Tubifex sp. on Fatty Acid Composition, Growth and Survival of Thai Mahseer (Tor tambroides, Bleeker, 1854) Larvae.

&lt;b&gt;Background and Objective:&lt;/b&gt; The high cost and limited availability of commercial live feeds have encouraged the use of locally available &lt;i&gt;Tubifex&lt;/i&gt; sp. as an alternative. This study evaluated the effects of enriching &lt;i&gt;Tubifex&lt;/i&gt; sp. with different fish oil sources on the fatty acid profile, growth performance and survival of Thai mahseer (&lt;i&gt;Tor tambroides&lt;/i&gt;) larvae. &lt;b&gt;Materials and Methods:&lt;/b&gt; &lt;i&gt;Tubifex&lt;/i&gt; sp. were enriched for 18 hrs with squid oil emulsion (TSO), sardinella fish oil (TLO), or striped catfish oil (TCO), while unenriched &lt;i&gt;Tubifex&lt;/i&gt; sp. served as the control (TNC). Larvae were reared from 7 to 25 days post-hatch and fed &lt;i&gt;ad libitum&lt;/i&gt;. Fatty acid composition was analyzed by gas chromatography and growth performance was assessed based on length growth, weight gain, condition factor and survival. &lt;b&gt;Results:&lt;/b&gt; Enrichment significantly increased lipid, polyunsaturated fatty acid and n-3 fatty acid contents in &lt;i&gt;Tubifex&lt;/i&gt; sp. (p<0.05), which were subsequently reflected in larval tissues. Larvae fed TCO-enriched &lt;i&gt;Tubifex&lt;/i&gt; sp. exhibited significantly greater growth and higher condition factors than those in other treatments (p<0.05). Survival remained high (97-99%) and did not differ significantly among treatments (p>0.05). &lt;b&gt;Conclusion:&lt;/b&gt; Striped catfish oil is a promising, cost-effective local lipid source for enriching &lt;i&gt;Tubifex&lt;/i&gt; sp. to improve the culture performance of Thai mahseer larvae.