Diana Walstad's Books and Articles

One Month after Tank Setups

The two tanks I set up a month ago for the big Expo on May 2 are ready for their road trip to Charlotte, NC to be displayed and then auctioned off. Pictures show tanks at setup and after one month. Plant growth is good. Readers please note that there are no filters or aerators. Do not need them in these tanks with their shallow depth, lots of good-growing plants, and a soil underlayer. Plants grow better without filters and aerators that just remove the ammonia and CO₂ that plants like.

**Photo Taken 3/29/2026.** Tank (left) for breeding fish set up 2 days ago; ‘Walstad Method’ tank (right) set up just hours ago.

**Photo Taken 4/29/2026.** The first month is always a race against time. Rooted plants need to take hold quickly to counteract “soil chaos” and outcompete algae. Looks like they have succeeded!

Tank on left (setup for fish breeding): I easily caught the 40 juvenile guppies that I was raising in it temporarily by removing all the little plastic pots with their plants. Plant growth in the bone-meal fertilized garden soil is good; I have had to trim the Vallisneria heavily and remove excess floating plants. Otherwise, they would take over the tank.

Tank on the Right (typical “Walstad” tank with soil underlayer): Plants and the ~15 Blue Dream Shrimp I added 3 weeks ago are doing quite well. (Will sell them with the tank.) I think that the substrate fertilization (See previous post) helped. (The potting soil I chose as the soil underlayer was perhaps a bit too infertile; its NPK was only 0.08/0.03/0.06.)

Fertilizing Substrates

In preparing my tanks for the May 2, 2026 Expo (See previous post), I noticed that the plants in the tank with a potting soil substrate were not growing as enthusiastically as plants in the other tank, which were in garden soil. What to do? Good rooted plant growth is key, and fertilizing the water just encourages algae. Unwilling to tear tank down and put in a new substrate… In a panic, I finally tried something mentioned many years ago on Aquatic Plant Central–insert frozen cubes of soil into the soil underlayer. So I froze cubes of my rich garden soil (Piedmont clay topsoil plus bone meal) and did my best inserting the cubes into the soil before they thawed. For good measure, I also inserted small pieces of 3 houseplant fertilizer sticks. Also replaced rock and attached Anubias nana with the beautiful Red Tiger Lotus. Results encouraging!

**Cubes of Wet Garden Soil** ready for freezing. I inserted these into a potting soil underlayer in the 10 gal tank where rooted plants were not growing that well.

I also inserted pieces from three of these sticks throughout the potting soil underlayer.

**Redo of the Tank** with added soil cubes, fertilizer pieces, and a Red Tiger Lotus in the center. Afterwards, a 30% water change and a little washed sand and gravel took care of the substrate disruption. Photo shows tank one day after the redo. It’s fun to play with soil!

BIG Expo Event Coming Up

Sustainable Reefs and I decided on my setting up two 10-gal tanks for their big event in Charlotte, NC on May 2, 2026. One tank shows the standard ‘Walstad Method’ with a soil underlayer as described in my Ecology of the Planted Aquarium. The other is described in my article ‘Potted Plants for Breeding Fish,’ which is freely available here on my website. Hopefully, the plants will get somewhat established to withstand the car ride to Charlotte. Photos show the progression so far. Work in progress… I am awaiting on my local glass cutters to provide the glass lids.

The Expo organizers are wonderfully dedicated to hobbyist education via their major events, which are attended by 1,000s of people with free tickets provided to schools, universities, home-school organizations, etc. Events feature both the marine world of beautiful, cultured corals and the freshwater world of fish, shrimp, and plants. Vendors of all kinds including me and a fish veterinarian! I will have—as I did last year in Raleigh—a table for selling my books. Only this time I will also have the two tanks and can talk about their setup, plants, and their cost. Tanks will be auctioned off at the event.

**March 29, 2026. Tank (left) for breeding fish set up 2 days ago; ‘Walstad Method’ tank (right) set up just hours ago.**

April 4, 2026. Fish breeder tank (left) now contains a few guppies; other tank some Neocaridina shrimp. All plants taken from my other tanks, so they are in the desired submerged form. Counting on them to grow fast!

Endler Guppy Cross

Preliminary results from crossing my Rainbow guppies with Endlers (Santa Maria strain) turned out much better than I expected, especially for the male Rainbow X Endler female matings. See photos of hybrid males at 3.5 months. LOTs of color! Females are also nice in that they have plenty of pigment in their caudal and dorsal fins, which the Endler females did not have. [Progeny from reverse cross (male Endlers X Rainbow females) were not nearly as attractive.]

I did this outcross, because my Rainbow guppies have had fitness problems last 2 years, probably due to accumulated inbreeding. Hopefully, infusing genes from these hybrids into my Rainbow stock will help prevent fluke outbreaks and increase longevity. Long-term project…

Hatching Brine Shrimp Eggs–Easy Method

For several years, I have been using my new easy “dish method” for hatching brine shrimp eggs. No air pumps. No daily saltwater preperation and disposal. The dish method works perfectly for my small-scale setup–feeding a couple of batches of guppy fry and juveniles. My previous (2020) article ‘Hatching and Culturing Brine Shrimp (Artemia)’ describes various hatching methods. However, it does not include the dish method, which I had not yet developed. It is by far the easiest. Enjoy!