# Metal Bioaccumulation by Carp and Catfish Cultured in Lake Chapala, and Weekly Intake Assessment
## 3 Results
### Pattern of Metal Bioaccumulation
#### 3.1.2 Non-Essential Metals: Cd, As, Pb, and Hg  
* Cadmium  
Figure 4a,b show the Cd accumulation pattern in the muscle of the catfish and carp. Muscle concentrations in both species were in the same range (1.3-3.67 mg/kg). The accumulation pattern in the carp showed a slight rise over time, but in the catfish, it was rather flat. Only carp showed significant differences in liver between experimental and control groups (Table 4). On average, Cd concentrations in carp were 78 times higher in the liver than muscle and 17 times higher in the case of catfish in the experimental group, revealing the concentrating function of liver in both species (Figure 4c,d). The Cd concentration in the carp  
Figure 4: Cd 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. liver was twice as high as that of the catfish at the beginning of the experiment, but by the end, it was almost 10 times higher (472.40 versus 51.56 \(\upmu\)g/kg) for the carps cultured in Lake Chapala only. The general pattern of metal accumulation had an upward trend in the liver of the experimental fish that was more prominent in the carp. The carp cultured in Lake Chapala had a significantly high concentration in liver with respect to the carp in the earth pond. * Lead  
Figure 5a,b show the Pb accumulation pattern in the muscle of the fish. The concentration ranges were very similar between both species and organs over time (Table 3). Only in the catfish muscle did the control group show a significantly higher concentration at the beginning of the experiment (Table 4). In the catfish liver, the Pb concentrations were on average 1.2 times higher than in the muscle. LCF between 11 to 23 was observed in carp liver, which gradually decreased after day 123 (Figure 5c,d). * Arsenic  
Figure 6a,b show the As accumulation pattern in the muscles of the catfish and carp. In this case, a downward trend of bioaccumulation was observed in the muscle of both species. Concentrations were slightly higher in the carp than the catfish, but within the same range (Table 3). As did not show statistical differences between groups (Table 4). The carps of the experimental group had on average 15 \(\upmu\)g/kg of As higher than the control group, but after 298 days of exposition, they reversed the trend. No liver concentration effect was observed for As in either species, as the concentrations were slightly lower than in the muscle throughout the study period (Table 2; Figure 6c,d). The catfish and carp livers had ranges of 11.47-87.34 and 38.35-126.08 \(\upmu\)g/kg, respectively. The general trend in the carp liver showed a soft upward shape, but the trend in the catfish was flat both in the experimental and control groups (Figure 6d). Figure 5: Pb 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. * Mercury  
Figure 7 shows the Hg bioaccumulation in the muscle and liver of the two species. Hg did not show statistical differences between groups (Table 4). No liver accumulation effect was observed in catfish, and soft LCF was observed in carp (0.3 to 5). In fact, in many samples, concentrations were below the method's detection limit (1.9 \(\upmu\)g/kg). Concentration ranges were similar between the tissues (Table 2), and lower in the carp (<1.9-18.59 \(\upmu\)g/kg) than the catfish (<1.9-34.56 \(\upmu\)g/kg). A slightly upward trend of bioaccumulation was observed in both species in muscle. Figure 6: As 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.