Guava Leaves from Swell UK are all harvested and dried naturally, and contain no pesticides. These are a great way to add a natural look to your aquarium, and can be mixed with any other leaf litter to add variation. As with other leaves, such as the Indian Almond Leaf, the natural tannins in these contain an antibacterial property which aids fish health.
Leaf litter like Guava Leaves in aquariums produce a biofilm that shrimp and other invertebrates will feed from, and even catfish will enjoy, particularly good for if you are away for a few days. These will break down naturally and slowly within the aquarium, so you won't get the pollution that many "holiday" foods can produce within a few hours of going into an aquarium.
These can take a day or two before they start to sink, and will be releasing their good bacterias for around 1 - 3 weeks, and will then start to break down. Ideally, leave them in for invertebrates to eat, and add fresh to continue their good work and provide a natural disease prevention for your fish.
These are completely natural and will vary from each piece, and there are 10 in a pack.