Fish Food 101
UNDERSTANDING LABELS & INGREDIENTS
Today, we all understand the importance of reading food labels. Aquarium diets often have ingredients not commonly found in other animal diets, and some specific knowledge when reading them will help you make an informed decision. There’s a lot of confusion surrounding the issue, and this makes it possible to manipulate the ingredient list to favor your own product while still technically following label requirements. This article’s goal is to help you become more informed and able to evaluate the reality behind the ingredient list.
Ash: Found in the Guaranteed Analysis (Analytical Constituents in EU labels), this is an item that seems wholly undesirable. Yet the story is a bit more complex. Ash is from the shells, scales and bones of marine animals that are high in calcium and phosphorus. Ash is also from the minerals in raw ingredients such as kelp and spirulina. Ash from these sources are beneficial in small quantities, but should be limited. Fish can only assimilate so much mineral content and any excess will simply add unwanted pollution to the aquarium water.
The presence of some ash is unavoidable. It’s important to understand that any food that uses whole aquatic protein ingredients like krill, shrimp or fish will have some due to shells, bones and scales. Some foods tout a low ash content; but if a food has low single-digit ash content, this can be an indication of using protein sources such as a large amount of soybeans, gluten…etc.
On the other hand, excessive ash content can indicate the food isn’t using whole ingredients, but rather post-processing waste: shrimp heads and shells, or fish stripped of their meat leaving tail and bones. If the ash content is high, the easiest way for a manufacturer to solve this is simply not list the ash content on their label — although any label failing to do so is not following U.S. or EU labeling requirements.
Whole Ingredients: For proteins, there are several ways manufacturers can misrepresent contents. A manufacturer can list items like lobster, shrimp, crab and/or a large variety of different fish in their ingredients to signify quality — but in reality be using leftover parts of the animals — aka post-processing waste.
Looking for the term “Whole” in the protein ingredients is a good indicator that the product isn’t using stripped leftovers. Another tip is Krill versus Shrimp. If a manufacturer is truly using krill, it isn’t possible to use anything but the whole animal, versus shrimp which can be separated.
The term ‘Whole’ is a better indicator of quality than the use (or non-use) of the term ‘meal’. The term ‘meal’ has become directly associated with ground post-processing waste. Many brands will omit the word ‘meal’ so as not to be associated with this. Yet if they don’t specifically indicate ‘Whole’, the ingredients may or may not be leftovers.
The result of these issues is that there’s an extreme range in the utilization of nutrients and overall digestibility within any ingredient category. Shrimp meal is typically comprised of cull portions not fit for human consumption: heads and shells, and many fish meals are likewise typically made up from the processing waste of the fish (not the whole fish). High quality food uses only krill, squid, whole fish, etc. — not leftover waste from processing plants.
Ingredient Padding: Another way manufacturers can make ingredients seem more plentiful is choosing to list several species of fish rather than use the term “fish meal”. This bumps binding agents (like middling and wheat flour) further down the list — while creating the illusion that a lot more fish protein is included in the formula. In reality, these “several variety of fish” are simply the various ingredients that went into the fish meal. Ironically, the reason for this variety is often that the meal is using cast-off odds and ends that were leftover.
The fact is, whether the meal is single source or made of a variety of species, a pound of meal is a pound — it doesn’t matter how many types of fish you used. It doesn’t represent a single gram of extra fish protein. This can be used to obscure the fact that the true second or third ingredient is a binding agent such as flour.
All prepared fish foods require a high-quality binding agent or they would simply fall apart in water. Premium foods use as little as 25% binding agent, while lower-quality foods can be as high as 50%. For the discerning hobbyist, it’s necessary to ensure that this “ingredient padding” isn’t being used to obscure the real contribution of these binders.
Mixing Dry and Wet Weights: The proportions of ingredients used in an aquarium diet are determined by weight. Brands can influence the order in which the ingredient is listed by using the ‘wet weight’ for those ingredients they want to list higher and the ‘dry weight’ for those they want less emphasized (implying that more of the premium ingredients are in the mix). A label should consistently use either the dry or wet weight for all the non-liquid ingredients; dry weight is generally the better metric, because once mixed and formed into pellets, this is the closest to the final product. Unfortunately, it can be quite difficult to tell if a food is mixing dry and wet weights from the label.
FOOD COLORING
For manufacturers, it’s tempting to make decisions that render the product more appealing for human customers at the expense of your aquarium companions. In dog food, this may be relatively benign ploys like forming the food to look like little pieces of steak or chicken (as if the dog cares!). Yet these tactics can be misleading and even compromise nutrition.
One example is food coloring. A manufacturer can use little of a common ingredient like spirulina, use green-dye to color the food a rich green, and promote it as designed for herbivores. Yet read the label closely — in some cases this “herbivore diet” is based on generic fish meal and contains little spirulina or aquatic veggies. Instead, it may be loaded with fillers like corn, middling, wheat or potato flour. The reality is: a nutritionally complete pellet for herbivores won’t be bright green naturally due to the need to mix plant matter with other nutrient-rich ingredients. However, any quality herbivore diet should have algae and seaweed as the top ingredients. Beware of pellet and flake foods that claim they are 100% spirulina: the raw ingredient is many-times more expensive than the sale-price of many so-called “pure” spirulina pellets or flakes on the store shelves — and that’s not even counting the cost of manufacturing it. Thinking this through, no business exists to lose money on every sale.
Brands will often use dyes for general color consistency to appease shoppers. Color variation is to be expected in any product using natural ingredients. Krill, for example, will have variations in color depending on season and water temperature during harvest. The same applies to most organics. As consumers, we’ve been trained to expect an artificial uniformity that manufacturers accommodate using dyes — which can find their way into your aquarium’s water.
Next, we’ll be talking about how you as the hobbyist can find the facts about fish nutrition for yourself so that you can make educated decisions for your aquarium health.