Why does phosphate have to be in food at all, since it’s a well-known algae nutrient?
Dr Kürzinger: Phosphate and phosphorous have to be viewed in different ways. For, on the one hand, phosphorous forms a major part of bone make-up and is involved in the important processes of metabolism. The phosphorous needs of fish have to be met so as to avoid problems of deficiency such as disrupted bone development or slow growth. On the other hand, phosphorous and phosphate are fish waste products and so also contribute to eutrophication and hence to overfertilisation in ponds. The more excessive or the more unusable the amounts of phosphorous that are contained in food in the form of phosphate, the quicker the pond becomes polluted, encouraging algae growth. By reducing the added phosphate content in new Tetra Pond Sticks by 25%, this unpleasant effect is successfully avoided.
Ms Tast, why are Tetra Pond Sticks of better quality than the products of other suppliers? 
Kristine Tast: Tetra Pond Sticks are an ideal complete diet for all pond fish and contain all essential nutrients, fibres and minerals as well as trace elements and vitamins for all-round biologically balanced nourishment – just as you would expect in nature. This way, pond keepers can be sure that by using Tetra Pond Sticks they are maintaining and improving the health and vitality of their fish. For the optimised mixture of nutrients ensures increased resilience, as bolstered by the patented BioActive formula. The sticks’ unique recipe and the top-quality ingredients prevent diet-related deficiencies. The sticks soften quickly for easy feeding and the high biological availability of nutrients makes them highly digestible. Thus we achieve excellent food conversion which in turn has a very positive effect on water quality. After all, the right care starts with the right feed.
Dr Kürzinger, at the company’s headquarters in Melle you work with around 20 colleagues on new product development and product improvement along with Biological Quality Assurance – what is the primary goal of your work?
Dr Kürzinger: Several requirements are always taken into consideration when developing Tetra products: the health of fish, high quality and high food acceptance as well as excellent water quality. All these aspects influence one another and so we are continuously working on balancing all the components with each other in the best possible way in order to put first-rate products on the market, since this is what the Tetra brand has long been known for.
Tetra Pond Sticks: 
Tetra Pond Sticks are ideal as a daily feed for all pond fish and are available in a variety of sizes. Sticks are supplied in 1 litre containers, 7 and 10 litre buckets and plastic bags holding 4, 7, 15 and 50 litres as well as in a new 40 litre size. The high-quality, resealable bags mean that the food is shielded from harmful factors such as sunlight, air and humidity. This protects the important substances inside and keeps the food fresh so fish get best possible nourishment.