We advise giving your fish DR. BASSLEER BIOFISH FOOD FORTE every three to four weeks as part of a fitness treatment for their long-term health. In addition to DR. BASSLEER BIOFISH FOOD REGULAR's premium ingredients, DR. BASSLEER BIOFISH FOOD FORTE offers immune-stimulating ingredients like citrus fruit pulp, premium glucan, and yeast and algae extracts. When dealing with stressful situations like illness, moving fish, or replenishing your aquarium, a 10-day fitness treatment with DR. BASSLEER BIOFISH FOOD FORTE is especially beneficial. The granulate sizes of DR. BASSLEER BIOFISH FOOD FORTE are M, L, XL, and XXL. All three water zones receive nutrients because the granulates in the smaller pellet size M sink gradually. This provides fish and surface feeders.