###### Abstract
Phytoremediation is an effective method for treating aquaculture wastewater, enabling its recycling and reuse. Aquatic plant species have been known to drastically reduce the total suspended solids (TSS), ammoniacal nitrogen (NH\({}_{3}\)-N), and phosphate from aquaculture wastewater [26; 27]. Water hyacinth (_Eichhornia crasysipes_) is one of several aquatic macrophytes used in phytoremediation alongside plants such as _Centrella asiatica, Ipomea aquatica, Salvinia molesta_, and _Pistia stratiotes_. WH exhibits rapid and uncontrollable growth, often completely covering water bodies. It is an excellent accumulator of heavy metals, making it highly suitable for wastewater treatment. The plant primarily absorbs contaminants through its root system [28; 29; 30; 31]. WH is a very fast-growing species and has a phenomenal growth rate. The maximum rate of biomass accumulation was estimated to be 20 gm\({}^{-2}\) day\({}^{-1}\), and the maximum relative growth rate was 1.50%/day. The peak efficiency of tissue storage relative to solar input was estimated to be 1.4%. The period of maximum growth occurs in April before the peak standing crop is attained (ca. 2.3-2.5 kg m\({}^{-2}\)) [32]. WH biomass generated from the phytoremediation system can be effectively used in energy generation, fertilizer production [33], biochar [34], ethanol [35], biogas, and methane [36; 37; 38; 39; 40]. The AcoD of lignocellulosic materials with highly biodegradable substrates is an effective strategy for enhancing the biodegradation of lignocellulosic [3]. Various studies have demonstrated that WH exhibits significant biogas potential when co-digested with other substrates [41; 42; 43; 44]. WH biomass has a substantial potential for generating energy via biogas and hydrogen [45; 46]. [PERSON] et al. [47] reported that the highest biogas production from WH using cow manure as the inoculum was 424.30 mL, with a maximum methane content of 64.38%. Additionally, a mere 6% increase in gas production with treatment with alkali pretreatment was reported by [PERSON] et al. [48]. The recalcitrant nature of WH may slow down the hydrolysis process and conversion to biogas [49]. The recalcitrant structure of WH can limit microbial degradation and result in slow digestion and reduced biogas yield [50]. The co-digestion of WH biomass with other substrates has been shown to improve the biogas yield. Adding a second substrate seems to improve the methane content and biogas quality [51]. Similarly, the co-digestion of WH with poultry litter produced significantly higher amounts of biogas than pure WH [52]. The combination of acidity and high fat and protein levels makes FW difficult to digest as a sole substrate in AD [53; 54]. As a potential solution to the digestion challenges of protein- and lipid-rich FW (energy-dense materials), incorporating a secondary substrate with different properties can help to address the digestion challenges associated with protein- and lipid-rich food waste. Few studies have investigated the co-digestion of WH and FW for biogas production [55; 56]. A notable research gap remains, particularly in enhancing biogas production through the AcoD of WH and FW. Therefore, the objective of the current study was to assess the potential for biogas production from FW and WH, using CD as an inoculum source. As the ratio of inoculum to substrate is a critical factor influencing biogas yield, the current study also examined the effect of ISR on the AcoD of WH and FW.