selv om de var ikke så store

Maybe they mean when they received fish.

It is "et minde, mindet, minder, minderne." You can always check any noun and their forms from Ordnet. Here it is for minde:

https://ordnet.dk/ddo/ordbog?query=minde

I also use this site to check for the past or perfect conjugations of verbs; and forms of adjectives. Very helpful!