Fish Tips & Hints

Comparing guaranteed analyses of frozen and dry fish foods

According to the FDA many state regulations require a pet food to guarantee the minimum percentages of crude protein and crude fat, and the maximum percentages of crude fiber and moisture. On our labels we include guarantees for other nutrients as well: the maximum percentage of ash (the mineral component) and the minimum percentage of phosphorus. The “crude” term refers to the specific method of testing the product, not to the quality of the nutrient itself. The guaranteed analysis test must be performed by a lab certified to analyze the nutritional composition of foods.

Guarantees are declared on an as packaged, as fed, or as is basis, that is, the amounts present in the product as it is found in the package. This doesn’t have much bearing when the guarantees of two products of similar moisture content are compared (for example, a dry fish food versus another dry fish food). However, when comparing the guaranteed analyses between dry and frozen fish-food products, one will note that the levels of crude protein and most other nutrients are much lower for the frozen product. This can be explained by looking at the relative moisture contents. Frozen fish foods typically contain 90-95% moisture, whereas dry fish foods typically contain only 5-15% moisture. To make meaningful comparisons of nutrient levels between a dry and frozen fish foods, they should be expressed on the same moisture basis.

The most accurate means of doing this is to convert the guarantees for both products to a moisture-free or dry matter basis.

To express each product on an equal dry matter basis we start with 100 percent as our base and subtract the labeled moisture level (100.0 – Moisture = Dry Weight). We then divide the amount of the labeled nutrient level (protein, fat, fiber, or other) by the dry weight and then multiply that number by 100 to get the dry matter basis nutrient level (Nutrient as Appears on Label ÷ Dry Weight × 100 = Dry Matter Basis Nutrient Level).

According to what appears on labels it looks as if dry fish food has a higher nutritional value than frozen, but when the water is removed from both products the frozen may actually have a better nutritional profile.

Resources for Comparing Guaranteed Nutritional Analysis
Guaranteed Analysis Converter
Dry Matter Basic Calculator for Pet Food
Clinical Nutrition Service

Phosphates in frozen fish foods

Where do phosphates come from?
Phosphorus is one of the most common elements in our environment and is essential to human, animal, and plant life. Phosphorus is present naturally in food, water, animals, and even human bodies. All fish foods are a source of phosphates.

When it comes to frozen fish foods there is a misunderstanding that the binders or gels used contain a high level of phosphates and therefore the food should be thawed and rinsed. This is not true. The phosphate levels in most frozen foods are between 0.05-0.1 percent, which is a negligible amount. Most dry fish foods (flake, pellet, freeze-dried, etc.) contain a phosphate level of 1.0 percent or greater. We list the phosphate levels of our foods in the nutritional analysis on all of our packaging.

If you feed your fish, you are adding phosphates to your aquarium and there is nothing that can be done to prevent this. Thawing out and rinsing frozen fish food before feeding will not remove the phosphates from the food. If you rinse frozen fish food a significant amount of nutrients that are beneficial to your fish will be lost.

Here is an excellent article by Randy Holmes-Farley, Ph.D., Aquarium Chemistry: Phosphate And Math: Yes You Need To Understand Both

Phosphate build up in an aquarium comes from many sources: uneaten food, plant decay, dying algae, fish feces, dead fish, and more. To help prevent high levels of phosphates from building up in your aquarium we recommend the following:

Avoid over-feeding: The more food you feed, the faster the buildup of phosphates, especially if the food goes uneaten. Fish can be fed frequently (1-3 times daily), but only what they can consume in three minutes per feeding.

Check chemicals and additives: Some aquarium chemicals and additives, such as pH buffers contain high levels of phosphates. To find out if the products you are using contain phosphates read the label, check the manufacturers website, or contact the manufacturer.

Remove dead leaves and decaying plants: These add nutrients in the form of nitrogen and phosphorus. Excess nitrogen and phosphorus will contribute to algae growth.

Perform water changes: The frequency with which water changes should be performed in an aquarium can be determined by using test kits to check your aquarium’s water parameters. Suggested desirable phosphate levels are as follows: freshwater and saltwater fish-only aquariums 0.05 ppm, reef aquariums 0.03 ppm, for planted tanks it can vary depending on your method of fertilization, so do your research and perform maintenance accordingly. A general rule of thumb for all aquariums is to perform a 20–30 percent water change every two weeks.

Siphon the substrate: This will remove decaying food and plant matter, fish feces, dead algae and more. Make sure you get into all the nooks-and-crannies, such as around the base of aquascape materials, decorations, and live plants. Siphoning the substrate can be done while performing a water change using an aquarium siphon with a gravel vacuum attachment.

Adding additional circulation:
by adding additional filters, powerheads, or circulation pumps you can help prevent waste materials from settling, allowing them to be captured by the filter and removed from the water column. Also remember to perform routine filter maintenance as materials trapped in the filter can break down and leach out into the water.

Add live aquatic plants to freshwater aquariums: plants take up both nitrates and phosphates for their growth. If your aquarium contains fish that eat or uproot aquatic plants consider incorporating terrestrial plants, such as pothos, there are tutorials online that show different ways this can be done.

Add macro-algae to saltwater aquariums: macro-algae, such as Chaetomorpha, Ulva, and Gracilari are plants, so just like freshwater aquarium plants they will take up both nitrates and phosphates for their growth. Most filter sumps have a compartment that can be used as a refugium and most all-in-one setups have a refugium compartment where macro-algae can be placed.

Use a protein skimmer: In saltwater/reef aquariums using a protein skimmer helps remove proteins dissolved in the water as well as the phosphate groups bound to these proteins.

Frozen fish food: To thaw or not to thaw?
A question we often receive is “do I need to thaw frozen food before feeding it to my fish?” In most cases thawing frozen food before feeding is not required. In fact, we recommend feeding our frozen cubes while still frozen, even to larger fish that are able to eat an entire cube in one gulp. The cube will float for 6–8 seconds and then begin to sink and break apart allowing fish to feed at their natural levels. Thawing out the cubes before feeding may not allow fish that feed at or near the surface to receive an adequate amount of food. Microwaving or thawing frozen fish food in hot water is not recommended, as this breaks down the nutrients contained in frozen fish food.
Why is water added to our frozen products?

As Necessary for Packaging
Adding water enables packaging equipment to properly pump and distribute food into blister-cube packs.


Preventing Freezer Burn
Adding water to frozen foods creates a protective layer called “glaze.” This layer provides protection against minor temperature fluctuations and freezer burn during transport and storage. It is an effective packaging aid for preserving the quality of the product. It helps protect the food items from freezer burn, because the surrounding ice sublimates first, instead of the water present in the food. The addition of water is especially important to help protect smaller less-meaty organisms such as bloodworms, brine shrimp, Cyclops, mysis shrimp, and rotifersfrom becoming freezer burned.

Product Performance
The addition of water also increases the buoyancy of the cubes. If no water were added the cubes would sink quickly when dropped into an aquarium. Because the cubes float and then sink they provide feeding opportunity for fish that prefer to feed at or near the water’s surface.

Product Integrity
Adding water helps provide support and rigidity to our flat packs. If we did not add water flat packs would be prone to damage during handling.

The benefits of feeding SFBB fish foods
  • All natural No fillers, no dyes
  • Highly nutritious
  • Our natural ingredients retain appearance and scent to entice finicky eaters
  • Free of harmful parasites and unwanted bacteria
  • Our high quality control exceeds industry standards
  • Convenient packaging/easy to use
  • For over 50 years SFBB has been widely recognized as the food of choice for fresh and saltwater fish
The advantages in feeding frozen fish foods
  • All natural no fillers, no dyes
  • Our product uses algin as a binder, a natural product derived from algae
  • Frozen foods allow fish to feed at their natural feeding levels
  • Our natural ingredients retain appearance and scent to entice finicky eaters
  • Free of harmful parasites and unwanted bacteria
  • Convenient packaging/easy to use
  • Better water quality in the aquarium due to a smaller amount of digested fecal matter being excreted by the fish
  • From an aquarist point of view, frozen fish foods create a feeding frenzy and it is fun to watch the fish eat
How to feed frozen fish food

We recommend feeding our frozen cubes while still frozen. This allows the cubes to float and release food as they begin to sink slowly. Simply drop a cube in your aquarium while it is still frozen, even for larger fish, that are able to eat an entire cube in one gulp. The cube will float for 6–8 seconds and then begin to sink and break apart allowing fish to feed at their natural levels. Thawing out the cubes before feeding may not allow fish that feed at or near the surface to receive an adequate amount of food.

Feeding Instructions: Drop cube(s) in aquarium while still frozen. The cube(s) will float for 6-8 seconds and then begin to sink and break apart allowing fish to feed at their natural levels. Feed often, but only what your fish will consume in three minutes. Remove any uneaten food. Never overfeed. Keep unused cubes in your freezer.

Important: Microwaving or thawing frozen fish food in hot water is not recommended, as this breaks down the nutrients contained in frozen fish food

Flat Packs
Our Frozen Flat pack foods can also be fed while still frozen. Simply break off a piece and drop it in the aquarium. However flat packs are most often purchased for feeding multiple tanks, in which case it is easier to thaw before feeding. Flat packs are also often used to feed larger fish because the food items are chunky or whole. To thaw flat pack foods break or cut small portions and thaw in a cup of aquarium or dechlorinated tap water until it is soft and starts to break apart, then pour in the aquarium or disperse to multiple aquariums using a pipette or turkey baster.

Feeding Instructions: Break or cut small portions and drop in aquarium or thaw in a cup, then pour in aquarium. Feed no more than fish can consume in three minutes. Never overfeed. Remove any uneaten food. Keep unused portion in your freezer.

Important: Microwaving or thawing frozen fish food in hot water is not recommended, as this breaks down the nutrients contained in frozen fish food

Natural Formulated Diets (i.e. Emerald Entrée, Marine Cuisine, Freshwater Frenzy, and others)
If these cubes are thawed in a cup, strained through a fish net, and then fed to fish a significant amount of nutrients will be lost. This is because they have leached into the water used to thaw the cube, therefore the nutritional value of the administered food will be limited. Some of the ingredients used in formulating these foods consist of fine water-soluble powders such as astaxanthin, Spirulina, and the vitamin premix. If you thaw SFBB’s Natural Formulated Diets frozen cubes before feeding it is recommended to thaw them in a cup of aquarium water and pour the entire contents into the aquarium without straining or rinsing.

Frozen Food Feeding Frequency
The Frequency with which you feed frozen foods can vary between fish species. Some aquarists like to offer one or two frozen ‘treats’ a week, while others like to feed almost exclusively frozen products — only infrequently supplementing with dry. All fish will enjoy frozen food when the opportunity arises.

What to do if frozen fish food thaws

Use of frozen fish food that has partially thawed
You may safely refreeze fish foods that still contain ice crystals and are cold to the touch or if they have been kept at 40° F or below for no more than 2 hours. Partial thawing and refreezing may affect the quality of some food, but the food will be safe to feed. If the temperature is above 40° F, throw it out!

If you keep an appliance thermometer in your freezer, it’s easy to tell whether food is safe. When the power comes back on, check the thermometer. If it reads 40° F or below, the food is safe and can be refrozen.

Treat completely thawed foods as follows
These foods are perishable. Do not refreeze completely thawed fish food. Spoilage may begin before bad odors develop and may be toxic. If you question the condition, throw it out!

Don’t use if odor is offensive or if the freezer temperature has exceeded 40° F for 2 hours or longer, throw it out!

Use common sense: If any foods have an offensive or questionable odor, DO NOT feed them to your fish.

How to feed freeze-dried foods

Brine Shrimp, Bloodworms, and Mysis Shrimp
Feed twice daily, but only what your fish will consume in 3 minutes. Remove any uneaten food.

Krill and Plankton
Presoak before using.

Tubifex Worms
Press cube of worms firmly against front glass below the water at desired feeding level.

How to feed Seaweed Salad

Tear or cut off a piece approximately 3 inches by 3 inches (for an average stocked 30-gallon aquarium) using a seaweed clip, attach to the inside glass of your aquarium in an area easily accessible for your fish. Your fish will “graze” at their leisure. Remove all uneaten seaweed after 6-8 hours.

Vitamins and Supplements

SFBB freeze-dried fish foods can be used to soak up liquid vitamins, supplements or medications for easy administration.