Studies of the physiological response of Pleco (Loricariidae) fed diets supplemented with astaxanthin coloration and under ammonia stress

• Main Authors: Itzamna Segovia Ubeda Cruz, 古伊蔓
• Other Authors: Chih-Yang Huang
• Format: Others
• Language: en_US
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/74738824511293100796

碩士 === 國立臺灣海洋大學 === 水產養殖學系 === 99 === This study evaluated two different areas; the first is the esthetic area of the ornamental fish business, as it was assessed the effectiveness of carophyll pink as color enhancer in Ancistrus cf. triradiatus var. albino. Different concentrations of astaxanthin supplemented in four regular diets were fed to Ancistrus cf. triradiatus var. albino. Astaxanthin concentrations in diets were 13.18 mg/kg (control), 20.65 mg/kg (low), 52.30 mg/kg (medium) and 208.61 mg/kg (high). At the end of the feeding trial, three color assessment techniques were performed, first Colorimetry, using the CIE (1976) L*a*b* color system and CIELHC color space, showing that different astaxanthin concentrations did not have any influence in skin lightness (L*) or yellow color (b*); diets with low and medium astaxanthin concentrations had higher red color (a*), (hue) and were more bright and color saturated. Secondly, spectrophometry was used to calculate total carotenoid concentration in the whole fish body, analysis showed that total carotenoid concentrations in the fish body were 3.78 mg/kg, 3.46 mg/kg, 3.36 mg/kg and 2.33 mg/kg for control, low, medium and high concentration, respectively. There was no significant difference observed among treatments. Finally, reverse phase HPLC was performed to detect total astaxanthin in the fish body, however, HPLC showed a higher concentration of a different carotenoid, Zeaxanthin. Astaxanthin concentration in the fish body were 21 mg/kg, 19 mg/kg, 16 mg/kg and 13 mg/kg in control, low, medium and high treatments respectively. Zeaxanthin concentrations in the fish body were 125 mg/kg, 112 mg/kg, 101 mg/kg and 70 mg/kg for control, low, medium and high concentrations, respectively. Statistical analysis showed that there was a negative correlation between feed astaxanthin and body astaxanthin concentration, also between feed astaxanthin and body zeaxanthin concentration. In second trial, the aquatic ecology of wild type and albino variations of two species of pleco from the family Loricariidae (Ancistrus cf. triradiatus var. and Pterygoplichthys gibbiceps) were investigated. Fish were exposed to various total ammonia (NH3/NH4+) concentrations in order to calculate the lethal dose which kills 50% fish (LD50) and investigate if there was any difference in ammonia toxicity between the two variants of the same specie. A series of acute toxicity test were carried out using the static test for a period of 96 hrs. Nominal total ammonia concentrations used in the different test were 0, 50, 100, 150, 200, 250 and 400 mg/l respectively, with constant temperature of 28°C. Being that many of the test fish died before the 96 hrs, the test was redesign to calculate the 72 hrs LD50, having the following results for total ammonia (NH3/NH4+) (TAN) and unionized ammonia (UIA) respectively: A. triradiatus wild type (188.97 mg/l TAN; 2.00 mg/l UIA), albino A. triradiatus (235.7 mg/l TAN; 1.59 mg/l UIA), P. gibbiceps wild type (122.58 mg/l TAN; 0.82 mg/l UIA) and albino P. gibbiceps (308.81 mg/l TAN; 3.28 mg/l UIA). The wild type variations showed greater susceptibility to total ammonia (NH3/NH4+) toxicity in both species of pleco. Unionized ammonia toxicity was independent of color variation. P. gibbiceps wild type showed the most sensitiveness to ammonia toxicity, while its albino counterpart showed the most tolerance. Keywords: Acute toxicity; Ammonia; Astaxanthin, Coloration, Feed, Loricariidae, Ornamental fish; Transportation; LD50