Can a small aquarium breed fish?

Small Aquarium doesn't breed fish at all. For cyclops voyages, you are going to want those chinese potatoes you have, and a couple of slots with Bulbo Trees. Use a knife on them to harvest, and they give 3Hunger/10Thirst. IMO, more beneficial to have than any other plant, as thirst seems to drain faster than hunger. Also, you may even want to swap those potatoes for Marblemelons that give 22/15, if I remember correctly. Cut one and it turns into 4 seeds, which take up 1 slot each, unlike most other crops, and when each of those turn into a full-size Marblemelon, harvest 3, and your hunger and thirst will fill rapidly.

These are only decorative. The large aquarium was added specifically to provide the breeding feature, so there is also little chance that the decorative aquarium will ever be updated to allow breeding.