# From Feed to Fish--Nutrients' Fate in Aquaculture Systems
## 3 Results
### Gaps in the Nutrient Budget  
The difference between the total output and input can be related to inaccuracies in assessments of individual budget terms or to the fact that some nutrient fluxes were not considered. Only 10 of the 23 papers that reported a total budget also specifically mentioned the unaccounted portion.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Reference**} & **Cultivation** & \multirow{2}{*}{**Fish Species**} & \multirow{2}{*}{**C (\%)**} & **kg ha\({}^{-1}\)** & \multirow{2}{*}{**N (\%)**} & **kg ha\({}^{-1}\)** & \multirow{2}{*}{**P (\%)**} & **kg ha\({}^{-1}\)** \\  & & & & **d\({}^{-1}\)** & & & & & \\ \hline \multirow{8}{*}{[13]} & \multirow{8}{*}{I} & _Barbietes goniotus, Cirrhinus mrigala,_ & & & & & & \\  & & _Cyprimus carpiro, Hypophthalmichtys molitrix,_ & & & & & & \\  & _Orechromis moliticus, Helostoma temmichtki,_ & & & & & & & \\  & _Oshromus gornay, Pangasus lympphthalmus,_ & & & & & & & \\  & & and hybrid catfish (Clarius marcephalus \(\times\) & & & & & \\  & & _Clarius garipines_ & & & & & & \\  & _Carrassing carassis_ & & n.r. & n.r. & n.r. & 55 & 1 \\  & _Iclutus mpatcatus_, hybrid channel catfish [16] & I (_Iclutus punctatus_ \(\times\) _Iclutus fircrafts_), & & 9 & 21 & n.r. & n.r. & n.r. & n.r. \\  & & _Polyloxacin garipulus,_ & & & & & & \\  & _Cattia culla, Labro rohita,_ & _Cirrhinus mrigala_ & 68 & 8 & 38 & 0.4 & 72 & 0.2 \\  & & _Cattia culla, Labro rohita,_ & & & 69 & 9 & 46 & 0.5 & 70 & 0.3 \\  & & _Orechromis moliticus_ & n.r. & n.r. & 31 & 1.2 & n.r. & n.r. \\  & & _Orechromis moliticus_ & n.r. & n.r. & n.r. & 64 & 0.6 \\  & & _Calsosoma macroopum_ & n.r. & n.r. & 19 & 0.7 & n.r. & n.r. \\  & & _Calsosoma macroopum_ & 70 & 24 & n.r. & n.r. & n.r. & n.r. \\  & & _I am M_ & _Calsosoma macroopum_ & n.r. & n.r. & n.r. & n.r. & n.r. \\  & & _I am M_ & _Calsosoma macroopum_ & n.r. & n.r. & n.r. & n.r. & 51 & 0.2 \\  & & _Oshromus gornay_ & n.r. & n.r. & 60 & 6 & 77 & 2 \\  & & _Icluturus punctatus_ & n.r. & n.r. & 23 & 0.45 & n.r. & n.r. \\  & & _Chamma argus_ and _Hypophthalmichtys nobilis_ & n.r. & n.r. & 60 & 0.7 & 82 & 0.2 \\  & & _Microperus salmonides_ & 16 & 11 & 45 & 3 & 69 & 0.09 \\  & & _Hybrid catfish_ (Clarius macrocephalus \(\times\) _Clarius_ & n.r. & n.r. & 40 & 8 & 24 & 0.9 \\  & & _garzipinus_) and _Orechromis moliticus_ & & & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 10: Contribution of sedimentation to the total output of carbon, nitrogen, and phosphorus and its rates (kg ha\({}^{-1}\) d\({}^{-1}\)). Values shown in the table are the mean of the values reported in the assessed papers. n.r.: not reported; I: integrated cultivation systems; P: polyculture; M: monoculture.  
In the studies where the estimated nutrient output was considerably smaller than the total input, this was attributed to missing input components, for instance, the introduced small fish and the influx of leaves and flowers, dust, and birds' feces [22]. When the total output was higher than the inputs, the authors mentioned overestimation of sedimentation [21], denitrification [17; 18; 31], loss to the groundwater and harvest of periphyton [30], nutrients in the outlet water [27], and the nutrient retained in the ponds [24]. Another possible reason that led to the unbalance between inputs and outputs could be the non-inclusion of inlet and outlet water when calculating the final balance [25].