## 3 Results
### Embryonic malformations in Zebrafish and African Clawed Frog
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Group** & **Concentration** & **24 hpf** & **48 hpf** & **72 hpf** & **96 hpf** \\ \hline control & - & 0 & 0 & 0 & 0 \\ \hline \multirow{4}{*}{F} & 0.1 ug/L & 0 & 0 & 11.1 & 0 \\  & 1 ug/L & 0 & 0 & 0 & 0 \\  & 10 ug/L & 0 & 2.9 & 11.8 & 2.9 \\  & 100 ug/L & 2.9 & 11.8 & 12.1 & 9.1 \\  & 1000 ug/L & 0 & 0 & 26.5 * & **26.5 * \\  & 10,000 ug/L & 5.9 & 5.9 & **23.5 * & **41.2 ** \\ \hline \multirow{4}{*}{C} & 0.01 ug/L & 0 & 2.9 & 0 & 0 \\  & 0.1 ug/L & 0 & 2.7 & 8.6 & 2.9 \\  & 1 ug/L & 0 & 0 & 0 & 2.8 \\  & 10 ug/L & 0 & 2.9 & 0 & 0 \\  & 100 ug/L & 0 & 2.9 & 2.9 & 14.3 \\  & 1000 ug/L & 0 & 0 & 0 & 2.8 \\  & 10,000 ug/L & 0 & 2.8 & 5.6 & 2.8 \\  & 100,000 ug/L & 3.0 & 5.9 & 2.9 & **17.6 * \\ \hline \multirow{4}{*}{F + C} & low & 0 & 2.9 & 11.4 & 5.7 \\  & medium & 0 & 0 & 0 & **18.2 * \\ \cline{1-1}  & high & 0 & 0 & 14.3 & 2.9 \\ \hline \end{tabular} Abbreviations: F—fluoxetine hydrochloride; C—citalopram hydrochloride; hpf—hours post-fertilization; low—fluoxetine hydrochloride 0.1 ug/L, citalopram hydrochloride 0.01 ug/L; medium—fluoxetine hydrochloride 10 ug/L, citalopram hydrochloride 100 ug/L, citalopram hydrochloride 100 ug/L, citalopram hydrochloride 100 ug/L.  
\end{table} 
Table 3: Malformations (%) in zebrafish embryos exposed to antidepressants as single substances and as a mixture. The results are related only to living individuals. Bold font and asterisks indicate a significant difference (* \(p<0.05\), ** \(p<0.01\)) between the control and the experimental groups at the same time of exposure. Figure 4: (**A**) Hatched zebrafish embryo in the control group at 96 h post-fertilization; (**B**) malformation of zebrafish embryo (oedema of heart and yolk sac, total body deformation) in the experimental group exposed to 10,000 \(\upmu\)g/L of fluoxetine hydrochloride at 72 h post-fertilization; (**C**) malformation of zebrafish embryo (body deformation, pericardial oedema) in the experimental group exposed to 10,000 \(\upmu\)g/L of fluoxetine hydrochloride at 96 h post-fertilization; (**D**) malformation of zebrafish embryo (body deformation, pericardial oedema) in the experimental group exposed to 100,000 \(\upmu\)g/L of citalopram hydrochloride at 96 h post-fertilization; (**E**) African clawed frog embryo in the control group at 72 h post-fertilization; (**F**) malformation of African clawed frog embryo (total body deformation) in the experimental group exposed to 1000 \(\upmu\)g/L of fluoxetine hydrochloride at 72 h post-fertilization. The incidence of malformations was significantly higher in the embryonic toxicity test on the African clawed frogs. Compared to the embryonic toxicity test on the zebrafish, malformations such as deformities of the spine and heart oedema were recorded in the control group (11.8% of living embryos at both 72 hpf and 96 hpf). Fluoxetine hydrochloride caused a significant increase in the incidence of malformations (especially oedema of the heart and yolk sac, deformities of the tail, spine, and eye, and increased pigmentation) compared to the control group in the experimental group exposed to 1000 ug/L at 96 hpf (41.2% of living embryos, \(p<0.05\)). A statistically significant difference was also observed in the embryonic toxicity test with citalopram hydrochloride. The experimental group exposed to 100 ug/L reported the occurrence of various malformations, such as deformities of the spine and tail, and oedema of the heart, in 52.3% of the living embryos at 96 hpf (\(p<0.05\)). Further, the combination of both antidepressants at the low concentration (fluoxetine hydrochloride--0.1 ug/L, citalopram hydrochloride--0.01 ug/L) caused a significant increase (\(p<0.05\)) in the incidence of malformations as well. A total of 41.2% and 50% of the living embryos showed some abnormalities at 72 hpf and 96 hpf, respectively. The most common malformations were yolk sac oedema, spinal deformity, and body shortening.