Its individual of course.But most of the times you can keep malas with bichirs/aros,docile cichlids who don´t try to bully the malan and other fun fish like odoes and such.But its important to get it used with tankmates at a very young age.
iv´e keept a friends almost 40cm mala with oscars,c.lucius ,bichirs and so on,i´ve also keept a 30cm (mine) with tankmate for a long long time (between 5-30cm) with gar,jag,wc oscar,bichirs,,bristlenose plecos and other fish.And i have a wc mala now around 30cm also with a big female jag,25cm f-gar,17cm odoe,20-25cm cb oscar + 18-20 wc aggressive oscar,20cm spotted clarias,8 bichirs between 23-38cm,17cm lucius and some bristlenose plecos.Never had an issue with one of them accept once when my cb oscar was young and started bullying the mala i have now.
Cichlids is not the best choice for tankmates.They can get too territorial and chace the poor wolf around the whole tank.
With tankmates they become quite docile and their reputation is far worse than the real truth...
I´ve also kept a couple of erythrinus before the malas..