# Metal Bioaccumulation by Carp and Catfish Cultured in Lake Chapala, and Weekly Intake Assessment
## 3 Results  
### Pattern of Metal Bioaccumulation  
#### 3.1.1 Essential Metals: Cu and Zn  
Table 3 shows the range of metal concentrations in catfish and carp obtained for every metal and the ranges of LCF for fish cultured in Lake Chapala, named the experimental group. Figures 2 and 3 show the pattern of nutritive metal bioaccumulation in muscle and liver of the cultured carp and catfish in experimental and control groups. Table 4 shows the differences between experimental and control groups, for every metal, species, and tissue. Cu and Zn did not show statistical differences between groups.  
* Copper  
Figure 2a,b show the Cu accumulation patterns in the muscle of both species and in both groups. A similar concentration range was observed in the muscle of both species (Table 3), but the pattern of accumulation showed large differences, as the concentration in the carp showed a steady increase over time, while in the catfish, a curve with a maximum on day 288 was observed. This behavior in carp muscle was observed in both groups, experimental and control.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Metal**} & \multirow{2}{*}{**Fish**} & \multicolumn{2}{c}{**Muscle**} & \multicolumn{2}{c}{**Liver**} \\ \cline{3-6}  & & **F** & _p-Value_ & **F** & _p-Value_ \\ \hline \multirow{2}{*}{Cu} & Carp & 3.017 & 0.168 & 1.213 & 0.820 \\ \cline{2-6}  & Catfish & 0.747 & 0.732 & 0.317 & 0.188 \\ \hline \multirow{2}{*}{Zn} & Carp & 0.722 & 0.679 & 2.797 & 0.198 \\ \cline{2-6}  & Catfish & 1.661 & 0.591 & 0.711 & 0.689 \\ \hline \multirow{2}{*}{Cd} & Carp & 0.361 & 0.240 & 156.912 & 0.000 * \\ \cline{2-6}  & Catfish & 1.038 & 0.965 & 0.301 & 0.213 \\ \hline \multirow{2}{*}{Pb} & Carp & 0.582 & 0.528 & 0.368 & 0.249 \\ \cline{2-6}  & Catfish & 0.008 & 0.000 * & 0.605 & 0.557 \\ \hline \multirow{2}{*}{As} & Carp & 0.793 & 0.786 & 0.253 & 0.158 \\ \cline{2-6}  & Catfish & 2.130 & 0.380 & 1.193 & 0.851 \\ \hline \multirow{2}{*}{Hg} & Carp & 1.247 & 0.796 & 0.429 & 0.433 \\ \cline{2-6}  & Catfish & 1.112 & 0.921 & 2.240 & 0.454 \\ \hline \hline \end{tabular}  
* Significant differences between the control and experimental group.  
\end{table}
Table 4: F-test to compare the variances of the experimental and control groups for carp and catfish, in muscle and liver.  
Figure 3: Zn accumulation in the experimental (\(\bullet\)) and control groups (\(\Diamond\)), in front of (**a**) muscle in carp, (**b**) muscle in catfish, (**c**) liver in carp, and (**d**) liver in catfish.  
Figure 2c,d show the accumulation patterns of Cu in the fish livers. Both species showed higher concentrations in the liver, but the carp had levels 22 times higher than in the muscle tissue (Table 3), 6.44-47.81 mg/kg in liver versus 0.36-2.39 mg/kg in muscle. The catfish liver, in contrast, showed an accumulation only three times as large as that of the muscle tissue (1.48-5.84 mg/kg in liver versus 0.56-3.83 mg/kg in muscle). The carp liver (6.44-47.81 mg/kg) also had a concentration 10 times higher than the catfish liver of the experimental group (1.48-5.84 mg/kg).  
* Zinc  
Figure 3a,b show the Zn accumulation pattern in the muscles of both species. The range of concentrations for experimental groups remained in a range between 5.66 and 16.05 mg/kg for both species, and the general pattern of concentration described a descending trend. The experimental and control groups showed similar patterns of bioaccumulation.  
Zn accumulation in the liver of both species was higher than in the muscle (Figure 3c,d). Zn concentrations in the liver began at similar levels in the two species, but a constant increase was seen in the carp. At the end of the experiment, the carp liver had 10 times more Zn than the catfish liver (265.00 versus 28.79 mg/kg) in experimental groups.