## 3 Derivation of Water Quality Criteria and Relevant Fish Assay
### Canada  
The Canadian Council of Ministers of the Environment (CCME) also has a national protocol for the derivation of WQS to protect aquatic life. This protocol requires data on algae, invertebrates, and vertebrates, particularly fish and amphibians [2; 27]; fish and amphibians are considered to be top-trophic-level organisms. In short-term exposures to determine acute toxicity in fish, two test species (_O. mykiss_ and _Gasterosteus aculeatus_) were exposed to chemicals for 96 h and LC\({}_{50}\) was used as the acute toxicity value [28; 29]. Considering the effective level of long-term exposure, test durations are determined in accordance with the developmental stage of the test species; the Canadian guideline specifies that exposures of longer than 7 days for early-life-stage embryos and larval fish or 21 days for juvenile and adult fish can be considered for chronic toxicity assays [11; 30].  
Environment Canada recommended two procedures for toxicity tests for early-life-stage fish using salmonid (_O. mykiss_) and _Pimephales promelas_[11; 30]. A revised biological test method using _O. mykiss_ included three options for developmental stages, namely embryos, alevins, and swim-up fry; embryo tests are conducted for 7 days after fertilization, the embryo/alevin test for 7 days, measuring the effect of each developmental stage after hatching, and the embryo to swim-up fry for 30 days. All these options start from the embryonic development and survival of early-life-stage organisms; since these early-life-stage organisms are at a sensitive stage in the life cycle, the assays are considered to be meaningful and powerful. Environment Canada also revealed the revised method of performing the toxicity test for 7 d to measure the survival of larval _P. promelas_[30]; seven days is not a long duration compared to a fish's life-span, but the larval stage is a vulnerable stage in the context of the entire life cycle [31]. Accordingly, the larval fish assay for 7 days'  
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Acute/** & **Test** & **Exposure** & **Test** & **Endpoints** \\
**Chronic** & **Guideline** & **Test Species** & **Stage** & **Duration** & **Endpoints** \\ \hline \multirow{8}{*}{
\begin{tabular}{c} OPPTS \\ 850.1500 [9] \\ \end{tabular} } & OPPTS & _Pimephales promelas_, _Cyrinodon variegatus_ & At least one life cycle & Survival, abnormality, behavior, reproduction, fecundity \\  & OPPTS & _Pimephales promelas_, _Lepomis marochitrus_ & Young fish 1 & \(\geq\)30 days & Survival, abnormality, behavior, reproduction, fecundity \\  & OPPTS & _Salvelinus fontinalis_, _Pimephales promelas_, _Lepomis marochitrus_, _Iclaturus punctatus_, _Cyrinodon_ & Larvae & Larvae & Survival, abnormality, growth, behavior, fecundity \\  & OPPTS & _Promelas_, _Lepomis marochitrus_, _Iclaturus punctatus_, _Cyrinodon_ & Larvae & Larvae & \(\geq\)30 days & Survival, abnormality, growth, behavior, reproduction, fecundity \\  & OPPTS & _Pimephales_, _Lepomis marochitrus_, _Iclaturus punctatus_, _Cyrinodon_ & Larvae & \(\geq\)90 days & reproduction, fecundity \\  & OPPTS & _Vareigatus_, _Mentidia mentidia_ & Larvae & \(\geq\)1 year) & & Survival, growth \\  & OCSPP & _Oryzias latipes_ & 12–16 wpf 2 & 19 weeks & (length/weight), organ damage, fecundity, reproduction \\  & ONCMP & _Oncorhynchus mykiss_ & & 60 dph 3 & Survival, hatching, growth \\  & OSCPP & _Lepomis marochitrus_ & Embryo & 32 d & growth \\  & _Pimephales promelas_ & & 28 dph 3 & (length/weight), abnormality, behavior \\  & _Orgzias latipes_, _Dunio rerio_ & & 30 dph 3 & \\ \hline \end{tabular}  
* Not applicable for non-feeding, spawning fish. 2 Weeks post-fertilization (wpf). 3 Days post-hatching (dph).  
\end{table}
Table 1: Cont.  
duration cannot replace chronic toxicity tests, but it can be used to predict the chronic effects of the conventional lethality test using juvenile fish (Table 2) [30; 32].