## 3 Derivation of Water Quality Criteria and Relevant Fish Assay  
### Us Epa  
The United States Environmental Protect Agency (US EPA) suggested the guideline for deriving WQS to protect aquatic organisms in 1985, and the revised version was released in 2010 [1]. This guideline proposed to protect aquatic eco-receptors, including fish, algae, and invertebrates, in freshwater and marine ecosystems. The toxicity data of fish are required, including acute and chronic data, which are essential for deriving WQS by calculating the acute-chronic ratio (ACR) for at least three other family groups of aquatic organisms.  
The ACR requires the acute and chronic toxicity values of fish [1]; the revised guideline suggested that short-term impacts, including mortality, and sublethal symptoms, such as abnormality or growth inhibition, should be used to estimate the effective concentrations (EC\({}_{x}\)) rather than lethal concentrations (LC\({}_{x}\)), which only reflect the mortality over 96 h of exposure (OPPTS 850.1085; OCSPP 850.1075) [20; 21]. Chronic toxicity can be assessed by the life cycle toxicity test. In US EPA, there are five test methods using embryos and larval fish. These test methods are conducted for at least 4 weeks [8; 9; 22; 23; 24; 25; 26]; Zebrafish and _O. latipes_ are exposed to substances for 28 days post-hatching (dph), with the observation of survival, hatching, growth, abnormalities, and behaviors performed. Using _O. latipes_, the extended one-generation reproduction test can be conducted measuring the sex-maturation-related endpoints, including gonad histology, fecundity, and reproduction rate [23]. The test period for chronic toxicity assessment can be applied differently depending on the life span of the test species [9; 24]. The fish species with short lifespans of less than a year are exposed for at least 30 days from the larval stages, and the species have a longer lifespan, 90 days of exposure are applied [24]. Additionally, at least one life cycle of substance exposure or short-term exposure of reproduction toxicity for 3 weeks can be applied [8; 25] (Table 1).  
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Acute/ Chronic** & **Test Guideline** & **Test Species** & **Exposure Stage** & **Test Duration** & **Endpoints** \\ \hline \multirow{8}{*}{Acute} & OPPTS & _Oncorhynchus mykiss, Lepomis_ & \multirow{2}{*}{Juvenile} & \multirow{2}{*}{4 days} & \multirow{2}{*}{Survival} \\  & 850.1085 [21] & & & & \\ \cline{1-1} \cline{5-5}  & & _Salmo salar, Menidia menidia,_ & & & \\ \cline{1-1} \cline{5-5}  & & _Lepomis macrodirus, Salvelinus_ & & & \\ \cline{1-1} \cline{5-5}  & & _fontinalis, Italurus punctatus,_ & & & \\ \cline{1-1} \cline{5-5}  & & _Oncorhynchus kisutch, Cyprinus_ & & & \\ \cline{1-1} \cline{5-5}  & OCSPP & _carpio, Pimephales promelas,_ & & & \\ \cline{1-1} \cline{5-5}  & 850.1075 [22] & _Poecilia reticulata, Poecilia_ & & & \\ \cline{1-1} \cline{5-5}  & & _reticulata, Orzzís latipes,_ & & & \\ \cline{1-1} \cline{5-5}  & & _Oncorhynchus mykiss,_ & & & \\ \cline{1-1} \cline{5-5}  & & _Cyprinodon variegatus, Menidia_ & & & \\ \cline{1-1} \cline{5-5}  & & _pentisulae, Dario rerio_ & & & \\ \hline \multirow{2}{*}{Not classified} & OPPTS & \multirow{2}{*}{_Pimephales promelas_} & \multirow{2}{*}{Juvenile} & \multirow{2}{*}{21 days} & \multirow{2}{*}{Survival, growth} \\  & 890.1350 [25] & & & & \\ \cline{1-1} \cline{5-5}  & 890.1350 [25] & & & & \\ \hline \end{tabular}
\end{table}
Table 1: Ecological effects test guidelines for fish, according to United States Environmental Protection Agency.