Table 4. Weight of evidence assessments for psychological outcomes.

First author and year	Weight of Evidence A: Quality	Weight of Evidence B: Research design	Weight of Evidence C: Relevance	Weight of Evidence D: Overall weight
Fish as companion animals
Kidd 1999 [81]	Low	Low	Low	Low
Langfield 2009 [52]	Medium	Low	Medium	Medium
Correlational studies
Lin 2013 [82]	Medium	Low	Low	Low
Intervention studies
Barker 2003 [53]	Medium	Medium	High	Medium
Buttelmann 2014 [62]	Low	Medium	High	Medium
Cole 2000 [83]	Low	Medium	High	Medium
DeSchriver 1990 [84]	Low	High	High	High
Edwards 2014 [54]	Low	Medium	High	Medium
Katcher 1984 [85]	Low	High	High	High
Maranda 2015 [86]	Medium	High	High	High
Riddick 1985 [60]	Low	Low	High	Low
Public aquariums
Cracknell 2016 [87]	Low	Medium	High	Medium
Cracknell 2017, Study 1 [61]	Medium	High	Medium	Medium
Cracknell 2017, Study 2 [61]	Medium	High	Medium	Medium
Sahrmann 2016 [88]	Low	Medium	High	Medium